Three Weeks After
It started innocently, when she saw that he was growing the TARDIS coral in his bedroom. He had managed to manufacture a makeshift sonic screwdriver from bits Rose and Pete had brought him back from Torchwood. It helped immensely with the process.
"What are you going to do when that's finished?" she asked, pointing to the coral.
"Oh, I dunno, traveling. What I've always done."
"You're… you're just going to leave again."
He caught the edge in her voice and looked round. "Not without you," he said. "Never without you, Rose. Never again."
"Have you ever thought… have you ever thought that maybe enough is enough?"
"I thought you'd be excited."
"Every place we go, something bad happens. And you always just… keep going. Sometimes it seemed like you were running. And I went with you. Because… because you're the Doctor, and that meant you knew what you were doing. But maybe you were just running. Is that what you're doing now, Doctor? Are you running away from all this? Is domestic life that terrifying to you?"
"Terrifying?" The Doctor stood up slowly. The hand holding the new sonic was numb. "Is that what you think I am, terrified? Rose, do you think this is easy? D'you think it's easy being human all of a sudden, being thrust into this when all my life I've been wandering, all my life I've been alone?"
"But you're human now," she said. "You said so yourself. You said you've only got one life. That you want to spend it with me."
"My body might be human," said the Doctor, "but my brain's not. I'm still a Time Lord inside, Rose, and that's all I've got left, don't you see? I've been separated from everything else, from my TARDIS, from all the planets I explored, all the things I did. Even from my own body. I've lost everything."
There was a deathly silence.
"You've still got me," said Rose.
"I'm lost," said the Doctor. He dropped the sonic onto his bedside table. It was difficult, very difficult, to keep from shaking, to keep his anger inside. Was it the new human chemicals in his body? "It used to be that wherever I went I could still be a little bit at home, I could still save people. I had my TARDIS, I was the Last of the Time Lords. Now I'm not even that. Even my body is alien."
"You spend so long defending us," said Rose. "After all that, you still consider us aliens? Am I an alien, Doctor?"
"Yes." He breathed it to himself. "Yes, you are. And so am I. I'm an alien to myself."
"If you'd rather go, then," she said, and stood aside.
The Doctor looked at the duvet, the well-used bed, the wardrobe. Sometimes he still felt unsteady on his feet. The single heartbeat where there should have been two was constantly throwing him off-balance. And the little piece of TARDIS coral in the windowsill, with bits of wire and metal strewn about it.
"Fine, then," he said, and swept past her. It was such an impulsive, human thing to do, but before he knew it he was out of the house and striding with purpose down the street.
As soon as Rose heard the front door slam, something cracked inside her, and she sat down on the bed and burst into tears. That's what you do, isn't it? Just leave us behind. That what you're going to do to me, Doctor?
No. Not to you.
It took the Doctor several hours of walking between streets, through back alleys and restaurant car parks, before he realized he was searching for a blue wooden box, and several hours more before he realized he wasn't going to find it.