She heals him with a look.
He breaks her with four words.
It's what he does, though. What he always does. He touches them, and they crumble to dust—change, die, live; it's all the same. No one is ever the same after having been touched by him.
Rose is no different.
Silly shop girl, she was. Slightly empty-headed, even if she was determined. Oh, she was never not smart; she always had enough intelligence to get by. But she never used it, never wanted to. No one had ever shown her that there was a reason to, that intelligence meant more than books and A Levels and getting a job. She was a typical twenty-first century teenager, caught up with fashion, movies, and living only in the moment. Normal.
Now she's brilliant. He had the privilege of watching her change, watching her grow—as time passes, she becomes more, uses that mind of hers and shines. She thinks and she figures; she grows and she lives. She's no longer small. Now she's bigger than him. Bigger on the inside.
He changes, too. Possibly for the first time, he really, really, changes. She digs his soul out of melancholy and self-hatred, and he grows. He learns to live because she taught him to.
Something of him is sucked into the other universe with her; something of her remains with him. They're both broken by it, and he knows that nothing will ever be the same again.
Until she's there, and he runs towards her. For one moment, he believes that everything will be all right.
Except it isn't. It can't be. He knows this, and he should have remembered. In the end, he always hurts those he loves. That's a pattern he's followed for nine hundred years, and there's nothing in all the universes that are going to let that change now.
Suddenly, they're back on that beach—a horrible place to have chosen, and he knows it, but it fits how he feels, knowing what he must do. There's no other option, now. It's the only way to give her happiness, to give her everything he's always wanted to, so he does what he has to do.
Rose asks him the question he wants to answer more than anything, and he prevaricates. "Does it need saying?"
Of course it does. But the other him had to say it, so that her anger—and she'll be as angry as she is heartbroken—is aimed at this Doctor. Not the part-human one. Not the one who can give her everything she deserves.
The other Doctor says it. Says "I love you," and this Doctor wants to cry. He thinks he might, even. Even though everything has worked out. Some might call it the perfect solution. He'll call it the perfect solution if anyone asks him. But Rose is kissing his part-human counterpart, and he walks away.
Those words might have broken her, but she'll heal. And it's better than the alternative, because he isn't just the Destroyer of Worlds. He's the Destroyer of Friends, and for just this once, he's going to make sure someone has a happy ending.
Even if it isn't him.
Author's Note: Just a short oneshot, this, but please review!