Wyn was excited about the trip to London. The Doctor looked extremely put out by it.

"I have taken you to a dozen fantastic planets and you're ecstatic about LONDON!"

"I've never been to London," she explained. "Dad and mum have loads of times. Dad does lectures and stuff and business meetings. But they never took me. They went to LA and New York and Sydney as well. I spent most of my life in boring Llanfairfach. Can we go see the London Eye and all the cool stuff?"

Rose and The Doctor both had the same memory of the London Eye as the transmitter for the Nestene Consciousness's deadly Auton attack on humanity, and they both smiled grimly at the idea of visiting it as a TOURIST ATTRACTION. But when The Doctor looked again at Wyn his eyes glinted with the indulgent smile Rose recognised as meaning he was open to any suggestion she wanted to make.

"Course we can go see the sights," he promised her. "But first stop is the less than glamorous spot by the bins at the Powell Street flats."

But he brought them there the exciting way, piloting the TARDIS by hand in fast free fall from temporal orbit, down through the atmosphere as England, then London, and the roofs of the flats came ever closer and even Rose was not entirely sure he was going to land safely. She and Wyn both grasped the console and screamed as if they were riding the greatest white knuckle roller coaster in the world. The Doctor grinned mischievously, a thrill-seeking control freak with his hands on a control that could bring them safely to land or smash a hole through the earth. The fact that even Rose wasn't absolutely 100% sure which he had on his mind added to the excitement.

"Well of course I'd bring you in safe," he said with mock indignation when they landed exactly centred on the square of yellow paint marked 'free parking for aliens'. "If I got us killed both your mums would kill me then grind my dead body and feed me to their dogs."

"Neither of our mums owns a dog," Rose said. "So you're safe."

"Mickey!" The Doctor cried as they crossed the courtyard. "Is THAT your new car?" He looked at the gleaming metallic blue Ford Focus that Mickey was carefully parking. "Very nice."

"No," he said. "It's Jackie's. Just had it cleaned and waxed for her."

"Mum bought a car?" Rose was surprised at first, then remembered that her mum was very well off now, thanks to The Doctor and his way with contracts.

"How's life treating you, Mickey?" The Doctor asked him as they all headed up to the flat.

"Very well actually, thanks to Jackie. Did you hear, she had a win on the lottery. She gave me a loan to set up the garage in a bigger premises. I'm not stuck under the arches now."

"That was nice of her," The Doctor said. He glanced at Rose and his expression clearly said "Don't say anything."

"Lottery win?" The Doctor stood in the kitchen door and looked at Jackie as she made coffee for all her guests. She looked at him and smiled apologetically.

"I wanted to help Mickey out. And I didn't want to tell him the money was from you for… well, you know. What with him and Rose…."

"Good thinking," he told her. "I don't suppose there was a way in the world I could ever have offered him the money. It would be too humiliating for him. This way, everyone comes out ok." He'd always felt guilty about Mickey. He DID take Rose from him, after all. If his money helped Mickey with his business, then it eased his conscience a bit. "And I notice you've spent a bit on yourself." The flat was looking very nice for having a professional decorator in and a fair slice of money spent on new furniture.

"That's ok isn't it?" Jackie looked at him anxiously.

"Well of course it is. There are no strings attached. It's your money, Jackie. I'm just surprised you didn't think about buying a new house."

"I thought about it," she said. "I looked at some houses. Near Wanstead Park. I always wanted to live there. Ever since I was a little girl. It was my dream. Nice detached houses with garages and gardens. But then I thought, I'd be all alone there. I wouldn't know any of the people. They'd probably look down their noses at me, because I come from a council estate. And I thought, WHY? Might as well stay here where I know people and they know me. So I told them I got a bit on the lottery. Everyone was dead chuffed for me." She looked at The Doctor. "Am I a silly bint? I had the chance to make my dream come true, and I stayed here after all."

"No, Jackie," he said. "I think you have it exactly right." She smiled and hugged him. "What was that for?"

"For being you," she said. "From the day you walked into our lives nothing has been the same. Oh, I hated you at first. I blamed you for everything that was wrong."

"I thought you still did."

"No. I was wrong. You're everything RIGHT around here." And she hugged him again and actually kissed him on the cheek.

"Mum, stop hogging my bloke," Rose said from the kitchen door. The Doctor smiled disarmingly and told her to grab the biscuit tin as he brought the coffee through to the living room.

Was this the man who didn't do domestic? Rose thought as she watched him hand out coffee mugs to everyone. What had she done to him? When she first knew him he was a restless spirit who barely sat down for more than five minutes, who always wanted to be in new places, always moving on. Now, Jackie's flat was almost his second home after the TARDIS and he sprawled on her new sofa, his long legs under the fancy glass coffee table and seemed completely content with the domesticity of it all. She had tamed him, reigned him in. And she felt as if she'd taken a proud wild animal from the open plains of Africa and put it into a tiny cage where it could barely turn itself around. It felt as wrong as that.

The Doctor looked at Rose. He had felt her thoughts and wondered how to allay her fears. She had it completely wrong. Unusual for her. Her instincts about him were usually spot on, but she was allowing doubts to creep in and they were clouding her judgement. He'd have to talk to her about that later.

"Doctor?" he looked up as Mickey called to him.

"Yes, Mickey," he said, giving his attention to him.

"I was wondering if you'd like to come down and see the new garage. I thought… maybe… you'd be interested."

"Yeah, course," he said.

"I thought we were going sightseeing?" Wyn complained. "A council flat and some old garage isn't my idea of London sights."

"You can borrow my car to go up town," Mickey offered. "Seeing as you hate London Transport, and the TARDIS isn't so good at getting the right place first time."

"My TARDIS is perfect," The Doctor protested, but he accepted Mickey's offer anyway, and after coffee they went with him down to his new garage.

"I'm able to take on three times as much work," Mickey said proudly as he showed them around. "Making plenty of money for all the lads. And I can ask Linda to marry me. Time I did, what with the baby due in eight weeks and all."

Rose was only just a few seconds behind The Doctor in offering her congratulations on both his impending wedding and his impending fatherhood. Mickey looked relieved as if he had wondered what her reaction would be. But seeing as SHE was engaged to The Doctor now, why WOULD she have any objections?

Money VERY well spent, The Doctor thought as he drank tea and talked with Mickey about his plans for the further development of his business and his personal life. He had never really been keen on the financial obligation of the Contract of Betrothal. It was the cause of too much unhappiness on his home-world. But this time it seemed to have been a force for good all around. He had Rose, Jackie had enough money to give herself a comfortable life, and Mickey was set on his way to the fulfilment of all his hopes for life. Who said money couldn't buy happiness?

The conversation was interrupted by the arrival of a breakdown lorry. All the staff stared at the car that was winched down onto the forecourt. Even Rose and Wyn, who were both fighting boredom at this point, looked interested.

"Wow," Rose said. "It's a DeLorean." Mickey laughed and said it was the only car she could recognise on sight. And only because of THAT film.

"Yes," she admitted. "I was never much good at being a car mechanic's girlfriend. But I've piloted the TARDIS through the asteroid belt. So if we're going to get the boys and engines sort of conversation going remember that the most fantastic engine in the universe LIKES me."

"Heck of a car though," even The Doctor admitted. Then he wondered why a police car had followed the breakdown lorry and shamelessly eavesdropped as the officer told Mickey that the car had been found abandoned in the middle of the Edgeware Road.

"Just abandoned? And nobody tried to nick it?" Mickey queried. The Doctor smiled. Mickey was not as daft as he looked. That was exactly the question HE would have asked.

"Well that's the thing," the policeman continued. "It's a bit of a puzzle. Nobody can open it. Not the joyriders or us! We've all tried. So we thought it had better come to the experts."

"Well, that's not exactly what I'm an expert at," Mickey quickly assured everyone in hearing as he booked the car in. "Lock-picking."

"The Doctor's quite good at that," Rose offered, and Mickey turned to him hopefully, but he just laughed and said it was time they were getting on. Mickey's mechanical problems were for him to sort out.

"DO you have a licence to drive a car?" Rose asked as she sat in the passenger seat of Mickey's Audi and watched The Doctor put it into gear to reverse out of the garage. It was so strange watching him do something as NORMAL as drive a car. She wondered if she could get used to it. He had talked more than once about giving up his wandering life when they were married, of them having an ordinary house, an ordinary life. She actually thought he MIGHT want that in at least one part of his complicated soul. But again, her conscience pricked her as she wondered how much SHE had influenced him, how much she had made the mundane seem attractive to a man who had lived his life so far outside of normality it made her breathless to think of it.

"Yeah," he said in answer to her question. "On Gallifrey, anyway! I was a pen-pusher for two hundred years. I drove to the office and back every day. Ok, it was a hover car and the motorway was half a mile above ground level. But the principle was the same." As he put on the handbrake and waited for the red lights to change at the junction he put his hand in his pocket and pulled out his wallet. From one of its deep recesses he took a card and handed it to her. She looked at the swirling holographic symbols that looked like the inside of a watch crossed with a doodle by Leonardo De Vinci and a Spirograph design gone mad. That was Gallifreyan writing. Her brain, under the influence of the TARDIS, translated it into the name, address and licence number of the middle aged man in the holographic photograph that she recognised as The Doctor when he was something like four hundred years old.

"So if we get pulled by a policeman because you forgot THIS car doesn't fly this is what you're going to show them?"

"No," he grinned. "What do you think I have the psychic paper for?" He glanced at the card in her hand. "That expired about three hundred years ago and the licensing office is space dust. I keep it because…. Because I'm a soppy article, as you are so fond of telling me."

Rose knew him well enough. She knew the slight catch in his voice that proved that it was more than being a "soppy article". The death of his planet was a grief etched on his soul for ever. As the lights changed and he reached for the handbrake he looked like he was concentrating on driving in London traffic, but she thought that was just his way of not talking about what hurt him the most of all the hurts he had ever suffered. She left him to his thoughts. There was nothing anyone could do to ease those hurts. He just had to work it out his own way.

Later, as he stood with his arm around Rose and Wyn, looking out over London from the very apex of the London Eye, he returned to the question of his domesticity.

"I liked my life on Gallifrey," he said. "I liked my ordinary day job. I loved my family. Coming home at night through the traffic jams just like anybody here in London, to my wife and my son, evenings by the fire listening to music, playing games, weekends in the mountains, long summer holidays off-world. It was a good time. It was in so many ways the best time of my life, that ordinary life that anyone here on this planet would recognise except for the flying cars."

"Better than travelling all over the universe and having adventures?" Wyn asked him. This seemed a strange mood for The Doctor. He was the one who had done so many amazing things. She'd heard about them all her life, even SEEN some of those things in the past few months. And yet he was saying that he WANTED the boring, ordinary life anyone else would give their right arm not to have.

"Yes," he said. "Because family is what life is all about - for all of us, no matter who we are or where we come from. And if I had the chance to be that man again… Yes, I'd give up everything I am now for that."

He felt Rose's thought then. She didn't say it aloud, but she was thinking it. That he was only saying these things for her sake. She thought she had changed him, and she was feeling guilty for it. But she HAD got it wrong

"Rose," he said gently. "You haven't done anything wrong to me. You haven't made me into anything I wasn't already. If I denied that I was… domestic… for so many years…. That was a lie. And I told it to myself until I believed it. Then you took my hand, and I saw it for the lie. And you gave me the hope that there is more to my life, more to the future than just keeping going, never belonging to any place or to any one."

"But why do you do it then?" Wyn asked. "Why do you spend your life out there doing dangerous things, trying to rescue the whole universe from danger?"

"Because somebody has to. And at the moment that has to be me. But I don't think it always has to be that way. I joke about retiring. But… but it doesn't have to be a joke. Someday, I am going to marry my Lady Rose and be truly happy."

"If the universe doesn't kill you first," Rose said quietly.

"It won't," he promised. And he hoped he could keep that promise.

It was late when they returned Mickey's car. The Doctor had taken Rose and Wyn to a nice restaurant after their sightseeing and then produced tickets for a West End show. Even so, he was surprised to find the lights still on in the garage and Mickey still trying to unlock the mystery car.

"I don't get it," he said as The Doctor came to look. "I've used everything bar the welding gear - I mean, you just wouldn't. Not on a car like this."

"No," The Doctor agreed. "I wonder… maybe I ought to have a go." Mickey stepped back and watched, Rose and Wyn standing by his side. All three of them knew enough of The Doctor's ways to expect interesting results now he had taken matters in hand. They none of them suspected just how interesting.

"$£$%*%€?" Rose giggled as she always did when he used Low Gallifreyan swear words. But at the same time, she knew he only did so when there was something worthy of such language, and she waited keenly for explanations.

"This is NOT just an ordinary car," The Doctor said. "This uses TARDIS technology." He bent over it again, taking readings with his sonic screwdriver. He looked up and around and saw Mickey, Rose, and Wyn all suppressing grins. He looked back at the car and the joke fell into place for him, too. "Ok, decide between you, which one of you is going to say it. Get it over with."

"Somebody…." Rose began.

"…has built a time machine…." Mickey continued.

"….out of a DeLorean." Wyn cracked up laughing as she said it. All three did. Even The Doctor allowed himself a smile, briefly.

"10 out of 10 for style," he said. "ZERO for originality." He adjusted his sonic screwdriver and pointed it directly at the lock. There was an audible click and he pushed the wing-style door up and over. "And minus a million for utter stupidity." Then his face turned pale and he turned away, breathing deeply as if something had made him feel ill. Rose looked at him in shock and stepped closer to the open car door. She looked just once and then she too turned away sickly. The Doctor saw her and clung to her hand as if it was all that kept him on his feet.

"What is it?" Mickey asked and started to approach the car. When he, too, saw the interior he turned and stopped Wyn from going near. "You don't need to see that, kid," he said as he put an arm out to restrain her. She protested about being called a kid, but he insisted.

"He's right," The Doctor said as he walked out to the garage forecourt. "Come here, Wyn." She came, and he put his arm about her shoulders gently. Rose looked at him and wondered why he was so affected by this. Yes, it was gruesome. But he'd seen much, much worse in his time.

"TARDIS technology," he said. "The only people in the universe who use that…. Are the Time Lords. MY people. That…. The body inside there …. What's left of it…. the blood is orange like mine. It's somebody from Gallifrey."

"A Time Lord? But…. We KNOW you're the only one. How…"

"I don't know. But…."

"Doctor," Mickey came out and stood beside him. "There is a mangled body bleeding out onto my garage floor. Regardless of what colour the blood is…. I have to call the police."

"No," The Doctor said. "Not yet anyway. Mickey…. Please… let me find out what this is about first."

"Well… I…" Mickey looked at him and thought he had never seen him look so intense. He was beyond upset. He looked back at the car, and the growing pool of sticky orange-coloured fluid. Time Lord blood? Was that REALLY what ran in The Doctor's veins? Was he SO different from them? He'd got used to The Doctor over the years. He'd got to like him. He thought of him as a regular, normal decent guy who just happened to have stolen his girlfriend from him. Then this reminded him all over again of just how far from regular or normal The Doctor was.

"Maybe you'd better," Mickey conceded. The Doctor thanked him and pulled his TARDIS key from his pocket. A moment later they heard the familiar sound as he brought his time machine into the garage by remote control. He went inside and came back in a very short time with something that looked like a portable laboratory.

"What are you doing?" Mickey asked as he watched him scoop up some of the blood and put it into a test tube. That was the last part of the process he understood. After that it looked just too much like alien technology. Mickey looked again at the interior of the car as The Doctor worked. There was, basically, no interior. Every bit of space was taken up by mangled machinery that looked as if it had been through the car crusher at the scrapyard. And there was no mistaking the fact that a flesh and blood being, something living, had been included in the mix. Orange blood seeped from the mangled metal, and just recognisable body parts could be identified. Mickey drew in a deep breath as he saw the blood-stained fingers of a hand just poking through the mess.

"Don't touch it," The Doctor yelled out. Mickey wasn't planning to anyway, but there was something chilling in his voice when he spoke. Rose knew at once there was something wrong - something more wrong, she amended. She drew closer. She tried not to look at the awful sight inside the car, but her eyes seemed drawn to it.

"What happened?" she asked. "What caused that to happen?"

"A faulty dimension circuit," The Doctor explained. Everyone looked blank. "It's what makes the TARDIS bigger on the inside. It makes it physically exist inside a small place. If a dimension circuit fails or is removed from a TARDIS the interior dimensions try to expand to their proper size. And since they can't, because they're inside a small space, they do one of two things - either they miniaturise everything until it fits even if the console room ends up the size of an egg, or in severe cases it all just crushes together into a mangled wreck. Either way, any living thing trapped inside is…."

"Uggghh…" Rose said. And she glanced at their own TARDIS.

"No," The Doctor assured her. "It would never happen to ours. It was properly and safely built by Time Lord engineers. The Dimension Circuit is made of non-destructible materials. Occasionally it forgets what size we all are - remember the fun we had with that apple - but it would never do this."

"Before I set foot in there again, I want that in writing, Doctor," Wyn told him. Rose didn't say anything. She had faith in the TARDIS. She had called it home for a long time and she could not imagine it harming her. All the same, she had never before considered what travelling in a machine that was bigger on the inside than the outside might mean. And she wished that thought would get out of her head.

"So who is…. Was…. THAT?" Mickey asked.

"That's what I'm trying to find out," he said. "This gadget is testing the DNA from the blood sample. It will tell me if the victim is an ordinary Gallifreyan with a double helix, or a transcended Time Lord with quadruple helix DNA and regenerative capability. It should also be able to tell me what family the victim was from."

The gadget beeped and a small printout emerged. The Doctor tore the paper off the roll and looked at it. Then his face turned deathly white and his eyes became pools of unbidden tears that he desperately tried to hold back.

Because he had known even before he ran the test that there was only one family the victim of this horrible accident COULD come from.

"Sweet Mother of Chaos!" he exclaimed as he gasped for air. He knelt by the open car door and reached for those dead fingertips and touched them gently. "Oh hell," he exclaimed as he failed to keep his tears in check. "Oh bloody, bloody hell."

"Doctor!" Rose came to him at once. "What's the matter? What is it? WHO is that? Is it somebody you know?"

"It's…" He stood up shakily and stepped away from the gruesome mess. He let her put her arms around him but there was no comfort in her embrace at that moment. "Rose… it's one of the boys…. One of the twins."

"Oh no!" Rose felt her own heart break. "No. How? Why? No. You must have made a mistake. It can't be."

"The DNA profile…. They… they have almost the same DNA as me… The Time Lord DNA that overwrites all human DNA… It overwrote Julia's blood when Christopher was born. Susan was her father's daughter. She was more of my side of the family than her mother. And… and her blood overrode David's so that her boys have her Gallifreyan DNA - My DNA. This…. This is the blood of one of my great-grandchildren."

"Oh my God!" Mickey exclaimed. He remembered the twins. He'd played football in the yard with them along with The Doctor. They were a great pair of kids. He couldn't take in that this….. that one of them was the person crushed to death by this contraption.

Wyn was already shocked to the core. She'd got a look at what they didn't want her to see after all and she was feeling sick about it. And knowing that the unrecognisable body - those PIECES of a body, chunks of flesh like something that came out of a mincing machine - were a relative of his was too much. She knew nothing about The Doctor's family, but she had enough feeling for other people's suffering to know it was just too terrible for him. She turned away and they heard the sound of her throwing up outside on the forecourt.

"You're going to do something aren't you?" Wyn asked him when she came back looking rougher than any of them. "You're going to make this not have happened. Isn't that what you do? It's why you are a Time Lord."

"He can't," Rose sobbed. "He can't change history. People have to stay dead. My dad… I tried to stop him being dead and it nearly caused the end of the world."

"But this isn't history, it's now," Wyn protested.

"It's the future," The Doctor said. "The boys live in the 23rd century."

"Well then, you CAN do something," Mickey said. "It hasn't happened yet."

"You don't understand the Laws of Time," The Doctor told him. "None of you do."

"No," Mickey admitted. "But we know YOU. And you can't let this happen."

"He's right," Rose said. "Doctor… I understand about my dad, about not changing history. But this… you have to do something. Because otherwise you'll blame yourself for teaching them to be able to do things like this. You'll eat yourself up from the inside with guilt. It IS the future. It hasn't happened yet. Even in the 23rd century, the boys are only eleven years old and they don't know how to begin building TARDISes yet. You CAN do it. You CAN. And… Doctor… For Susan…. Think of her… you HAVE to."

"Rose…." The Doctor held her tight in his arms. He kissed her forehead and just held her for a long, long time. Then he made a decision.

"You have to stay here," he said. "Rose, you and Wyn stay here with Mickey. I have to do this alone."

"What can go wrong?" she asked, fear compounding her grief.

"I could unravel time backwards and cause the end of the Earth before it was even created," he said.

"Try not to do that, Doctor," Mickey said as he came and gently took Rose's hand in his and drew her away from him. He took hold of Wyn too, and they all three watched as The Doctor went to the TARDIS. The door shut and all was silent for a few minutes before it dematerialised. Time didn't unravel. But none of them would count on it not happening until The Doctor was safe back with them and he had "made this not have happened." Wyn's phrase, despite her complete disregard for the rules of grammar, expressed it exactly.

The Doctor looked at the data on the TARDIS viewscreen. Before he had dematerialised he had scanned the DeLorean. Its databanks were almost unsalvageable, but he had coaxed the most valuable piece of information from them - the co-ordinate in space and time where it had come from on its one and only journey.

He fed the co-ordinate into the navigation console.

Actually, he put the time back ten minutes so he would get there in time to do something about it. And as he felt the TARDIS respond he grimly remembered that was what the kid in the bloody film did, too. Centuries of time travel experience and he was trapped in a 1980s science fiction joke.

But what had happened to one of his great-grandchildren was NOT a joke. He tried to put the memory of what he saw out of his mind, telling himself he was going to sort it. But he wasn't entirely confident that he could. Yes, changing something that was going to happen in the future was different from changing something that had already happened in the past. But he couldn't help feeling it was a matter of semantics.

If the Time Lords were still around they certainly would not allow him to do what he intended to do.

Their Laws of Time had stopped him from saving his son and daughter-in-law. How easy would it have been to slip back a few hours that awful day and stop them from getting into the car. But he'd have been arrested and subjected to a penalty nearly as extreme as the man who murdered them had suffered. And beyond the laws laid down by his people there WERE the physical limitations of reality. That was why Rose's dad was dead, why Christopher and Ámándáliá were dead, why his whole planet was dead. Because those things were in the past and they had to stay that way.

But changing the future was not the same as changing the past. It was just like any ordinary person deciding to give up drinking or gambling and make amends to their lives, change their destiny. If he did it right, he COULD do this.

He had to do it. Because Rose had been right; he couldn't live with himself if he didn't. He was the one who had taught the boys all they knew about being a Time Lord. He put it into their heads that they could do anything. It was his fault that at some point in their young lives they decided to build their own TARDIS. He even gave them the DVD of that bloody film. Naff as it was there were some lessons about the dangers of time travel in it that he wanted to get across to them without seeming to be nagging. He never expected them to actually FIND a DeLorean and have a go at it.

Where exactly DID they find one in the 23rd century? He made a note to ask them when the crisis was over.

Chris and Davie Campbell looked at each other. They were apprehensive, but also excited. This was their biggest project yet. Their own time travel machine based on the blueprints from their great-grandfather's TARDIS. And it was the coolest looking machine too. Ok, they ripped the idea off. But who in the 23rd century had seen that film other than them?

"We'll go back in time and sue the film producers for pinching OUR idea!" Chris said with a laugh. Then he looked at his brother and knew he really was just a bit scared about doing this. "It'll be okay, don't worry."

"Yes," Davie said. "But you know...."

Chris did know. He always knew what his brother was thinking.

"We should have asked Granddad to give it a once over," he said. "He REALLY knows about this sort of thing."

"But he's never actually BUILT a TARDIS," Davie reasoned. "His came from Gallifrey. I'VE got more knowledge of how they REALLY work from scratch."

“We’ll tell him after we’ve done a successful test. When we can prove we know what we’re doing,” Chris told his brother.

“Anyway,” Davie added. “I suppose if he knew what we were doing he’d stop us.”

"Too bloody right I would," The Doctor said. The twins both turned around in surprise and guilty shock to see him standing there, leaning on the door frame of the lock up garage where their top secret project had been built.

The Doctor was surprised too, even though he knew that he'd gone further into the future than he usually did when he went to see them. They were only eleven years old in the personal timeline he knew them in. But this was eight years later. They were nineteen years old. They were young men. They looked a lot like he did as a teenager; tall, dark haired and dark eyed, pale-skinned from spending too much time indoors fiddling with temporal mechanics and not enough time out in the fresh air. They also had that air of cocky invincibility that all teenagers tend to have, especially Time Lord teenagers with the universe at their feet.

They still looked identical in their features, but Davie's hair was short and he had artificial blonde streaks in it, while Chris wore his hair long, tied in a pony tail, like The Doctor remembered doing when he was about a hundred and fifty. And he still wore the silver crucifix he had been given by an Elizabethan seminarian when he was ten years old. Neither of them had any particular religion. They knew they belonged to a race that WAS worshipped as gods. But Chris had his own reasons for keeping that symbol of Earth piety and nobody had ever disputed it.

His first instinct was to hug them, tell them of the surge of pride in his hearts at the wonderful pair of young men they had grown into. But his grief and worry about what they were about to do overrode all those feelings. He stayed where he was, watching them carefully. Ready to physically restrain them if either tried to go near the car. But knowing that was the last thing he should resort to.

"Granddad!" Chris looked nervous. He felt like he'd been caught with his hand in the biscuit jar. He knew his great-grandfather was angry with him, even though there was nothing in his expression to indicate it. "I know we should have told you. But we wanted to do something on our own. We wanted to prove to you that we could… that we were ready."

"I have no spur - To prick the sides of my intent, but only Vaulting ambition, which o'erleaps itself - And falls on the other."

"Huh?" The twins both stared at their great-grandfather and wondered why he was quoting Shakespeare at them.

"Should have been the motto of our family," he said. "Vaulting ambition… We always wanted to run before we could walk. It was always my chief fault. And it's my fault you two have it in concentrated amounts. The youngest Time Lords ever. Two hundred years of learning in less than ten. I rushed to make you what you are. Of course you want to charge ahead and do it all. And of course you're not going to listen to me telling you not to do it. And if you want to build a TARDIS for yourselves, then how can I stop you? But…Do just one thing. Please. Don't either of you set foot in that machine until you have done a dry run on autopilot."

"Why?"

"Don't ask. I can't tell you. I shouldn't even be here. But please, do that. That's all I ask."

Why is he blocking his thoughts from us?" Chris asked his brother telepathically. "Can you get through?"

"No." Davie replied. "But something is wrong. He's not just angry. We know angry. He's…."

"Sad," Chris said. "Horribly sad. Like something really dreadful has happened."

Davie looked at his brother, then his great-grandfather, who hadn't moved an inch and had said nothing more. Then he turned to the time machine that stood, doors open, in the middle of the garage. He went to it and set its co-ordinate to dematerialise and rematerialise three minutes from now in the same place. He stepped back and closed the door. The car began to emit a sound almost exactly like the TARDIS their great-grandfather had so often taken them into time and space in, the one they had learnt to fly as well as he did. The sound was a little higher pitched, perhaps. But that didn't mean there was anything wrong.

"Perfect dematerialisation," Davie said, trying not to sound TOO triumphant. "Now just wait…"

They waited. Three minutes later they heard the sound again, fading in like an old fashioned analogue radio being tuned to a channel. And the car stood again in exactly the same place it had disappeared from.

"See!" Now he WAS triumphant.

"Open it," The Doctor said. Davie looked at him and felt a little less sure of himself. He stepped up to the car and unlocked the door.

As he stared at the mangled wreck of tortured metal that filled every millimetre of space he had a vision of what would have happened if he'd been inside. He didn't need to look at his great-grandfather to know now what it was he had blocked from them. He felt his brother's arm around his shoulder, felt his horrified realisation of how close to death one of them had come. He hugged his brother tightly and felt glad to be alive.

"Granddad… how did you know?" They both turned and looked. But he was gone. On the edge of their hearing they heard the sound of the TARDIS dematerialising.

Rose ran to embrace him the moment he stepped out of the TARDIS. Wyn was close behind and she too hugged him. Mickey stood back from them. Group hugs with The Doctor weren't quite his thing. But he couldn't disguise the fact that he was utterly relieved to see him.

"The car disappeared," Wyn said. "And the blood."

"I made it not happen," he said.

He hadn't, in fact, DONE anything. That was the key to changing things without upsetting the fabric of reality. He hadn't disabled the time machine. He had simply told the boys they needed to do a dry run first. Davie had set the co-ordinates and sent it on that dry run. Davie had realised the fatal mistake he had been about to make.

As for the past, the principle was the same. If - for example - they had gone back to, say, October 1986, when Sarah Clarke was trying on wedding dresses, and suggested to her that it would be much nicer to have the wedding AFTER the baby was born, when she had got her figure back and she could buy a size smaller dress, then Pete Tyler wouldn't have been on that road that day. THAT was how you changed the past without ripping open the fabric of reality. It could be done that way. He knew that. There were moments when he felt he should tell Rose that, and let her decide if they should. Then he reminded himself of all the other things he wished he could change and couldn't, and decided the past, imperfect as it was, had to stay that way.

But the future was another story. And he was deeply relieved that there WAS a future now for his dearest blood.

"Let's go home," he said.

"Home?" Rose queried.

"The TARDIS," he said. "Home. Guaranteed no dimension circuit failures. Money back if wrong. I'll put it in writing if you like."

"Home!" Rose smiled and took his hand. Wyn came with them. They went into the TARDIS and left the door open while Mickey locked up the garage and turned out the lights, then, he too came with them for the short hop back to 'free parking' at the flats.