Too old.

He tried to tell her this, naturally, as she was moving closer with that look in her eyes. There are hormones raging in her, he can nearly smell them, and the Doctor's hearts seize up. Whatever is about to happen, whatever she has planned, no matter how much he wants it, has to be stopped. So he tries to tell her that he is too old. He sputters and the words don't quite come out, but she pauses and he knows she understands what he was attempting to tell her. He is too old for this, for her. Setting his real age aside, he looks old enough to be her father, and she'll never be happy if she settles for old, daft him when there are so many pretty boys out there that would fall over themselves for a chance to touch her.

Not that he doesn't fall over himself at the chance to touch her. Whenever he can, he falls over himself at a half chance and she must have noticed at some point- all the hand holding, all the hugs, all of the casual touches that, when summed up, amount to something much more than casual. She had to have noticed. She's a smart girl, no matter how many mistakes she's made, and she's got to have noticed.

Of course, the Doctor liked to imagine that she was reciprocating when she'd take his hand- his old, battered, scared hand. He liked to imagine that she genuinely enjoyed the feel of his big, calloused hand curled around her tiny, soft one. He liked to imagine that when what-is-certainly-not-about-to-happen actually happened, it would be out of a genuine love of him and not some lustful, human need.

Though, truth be told, he wouldn't mind fulfilling every single sort of (aching, throbbing,) lustful human need if it was Rose Tyler's (aching, throbbing, trembling, wanton, and all of those other adjectives that, really, make him cringe a little- because who honestly thinks the words aching and throbbing are appropriate to describe the white hot lava that is desire?) need. He'd eagerly give up his last few regenerations for that sort of heaven, even if in the end it did leave his hearts broken. And if it would make Rose happy…

But that's another matter entirely.

And thinking about it is not helping. Rose's mind has caught up with his words, and she just shakes her head and grins, her tongue poking out between her teeth. She says something like, doesn' matter to me if you're five thousand an' seven and she starts moving towards him once more.

The Doctor takes another step back. He tries again.

Too strange.

Rose outright laughs at that one, casting her eyes around the TARDIS. You live in a bloody huge space ship that's bigger on the inside than the outside, mate, he thinks she says, an' I've seen Gelf an' Daleks an' Slitheen. Strange is pretty common 'round here, an' I happen to like strange. Normal never did sit well with me.

No, of course that wouldn't work on Rose Tyler, the girl who managed to have sympathy for a paper-thin piece of skin with lips that had tried its damndest to kill her. Rose was always surprising good with the bizarre. The Doctor's mind races.

Too dangerous.

Rose simply rolls her eyes. The Doctor has to give her that one- dangerous is bread and butter to them. Common as soap. The word dangerous had lost its impressiveness for Rose several dozen trips ago, if it were ever impressive at all. She's still advancing on him and the back of his legs hit the TARDIS console and she's too close to duck around without giving her an excellent opportunity to grab him. He is trapped.

Too broken.

He doesn't mean to say it, really, he doesn't. The last thing he wants is Rose to think that he is a fragile, porcelain doll but in a way he supposes it is true. The Time War left him with so many regrets, so many heartaches. Micro-fractures running across his body, mind, and hearts for every person he lost, everyone he could not save, every hurt in nine hundred years of life. He hates, hates the cliché of it, but one more might really break him. Rose Tyler might be the straw that breaks the Doctor's back and crumbles him into so much Time Lord dust.

Rose softens, her eyes loose some of their predatory edge, and the Doctor thinks that, just maybe, he can give her an easy way out that will spare both of them heartbreak, so he keeps talking. He doesn't think, he just lets his lips move and hopes. Words like Time War, and used to be a father, Rose, and last of my kind, you don't need somethin' like that weighin' on you pass his lips. You deserve someone whole and young, and I can't grow old with you, Rose, it isn't physically possible for me and I couldn' take it if this- what you're suggestin' right now- was just a fling.

He snaps his mouth shut, but it is too late. He can not reestablish a filter between his mind and his mouth before five traitorous words have flown past his lips: I love you, Rose Tyler.

She gasps. The Doctor has gone into shut down out of sheer panic and her expression does not quite register. The grin spreading across her face, her slightly misty eyes, and the hand coming up to shakily touch her lips goes totally unnoticed. With all of his Time Lord brilliance he manages to think that maybe he is projecting his fantasies onto her in real time- because really, with how studiously he's been repressing his desire for her it'd have to happen eventually. He knows that in a moment he will come to his senses and realize that he is alone in the control room and that Rose is packing her bag and demanding to be taken home.

When she kisses, when those beautiful, full lips of hers press hard against his and her hands are sliding up under his jumper, the Doctor thinks, oh. He smiles. He crushes her closer.

Fantastic.