The Doctor found it easier to become a human than the last times he'd tried. He went through the TARDIS and found the basics he needed, along with a few extra things he could sell in the event of an emergency. Then he locked the TARDIS and left it in junk yard a few miles away from the Powell Estate, taping signs on it such as "Lost cat," "Looking for work," or "Have you seen this man?" for good measure. He stepped back to admire his work.
"Not the best look for you, but it'll have to do."
The flat was smaller than he would've liked. After all his time with the TARDIS, he kept expecting the closets to be bigger on the inside. He found work at a repair shop, what with his brilliant skills. Playing idiot was harder than it looked, however; he kept wanting to burst into technobabble.
Within a week after getting settled in, Rose payed him a visit.
"Hello," she smiled. "I'd heard you moved."
"Yeah," he smiled at her. Rose. Rose. His Rose.
"Well, I just came to say hello."
"Yeah."
"So where are you from?" Rose asked.
"Here, sort of."
"Oh."
"My..." Mickey had said something about a deceased grandmother, hadn't he? "I lived with my grandmother. Grew up with her. She passed away a few years back..."
"I'm so sorry."
"It was my fault. She fell down the stairs," You're making up a sob story? What's wrong with you? Stop lying. This is taking Rule #1 to the extreme. "I'd always told her I was going to fix it, but I never got around to doing it."
Rose frowned. "It wasn't your fault. You didn't make her fall."
"I know." Well, your grandmother is dead. And it was your fault, you're just changing the details to make understandable to a human. That's all.
Rose started talking about her friends and her school, and it dawned on him that she was only seventeen. Still in school, no idea what was to come in a few years time. Saving the world, fighting monsters, getting her heartbroken... Part of him wanted to stop it all from happening. To stop him from ruining her life. But he couldn't. He really was a stupid, selfish old man.
"Well," Rose said, after a few hours of talking, "I should go. It's getting late."
No, don't go. "You could stay for dinner."
She smiled. "Um, I'm sorry. I have a date with my boyfriend. Maybe some other time."
Oh, right. Boyfriend. He should've remembered that. She'd had a boyfriend before "Mickey." Jimmy Stones, wasn't it? "Yeah, maybe another time."
She nodded. "Bye, Mickey."
"See you later."
As soon as he was gone, he ran to the junkyard and burst into the TARDIS.
"Access companion file: Rose Tyler."
Rose's voice interface appeared. "Rose Tyler," it said. "Born April 27th, 1987. Joined the TARDIS March 2005."
"I know that. What about her life? From 2003 to 2005. What happened then?"
"Records not available."
"Why not?"
"Foreknowledge denied."
"What? You mean I have to... just go with it?"
"Yes."
"Well that's no help."
"I know."
"Oh, you're getting a sense of humor now. That's nice. Thanks a lot, dear!" he shouted as he left, earning stares from a few of the people passing by.