When he looks at her, it's like nobody else is in the room. She glows like a radiant sun and just brings light to everything she touches. All she has to do is smile that smile or widen her eyes a bit or just flip her hair and it's like he's putty in her hands.
He shouldn't be.
Because he is a time lord and she is just a human, an ape. He shouldn't even be good friends with her… really good friends.
More than friends
Less than lovers.
He doesn't even know.
All he knows is that he loves her, he loves her so much. He loves her more than he has ever loved anyone before, and it frightens him. How can one small human have such power over him and that he melts under her gaze. All he knows is that he loves her, that if it meant he could be with her he would live in a house with carpets and doors and windows and get a mortgage.
He wants curtains and a dining table and a breakfast bar and he wants to hear about her day and tell her about his and look at her every chance he gets. He wants to have kids with her, two or three or even four, little blonde humans with those gorgeous brown eyes and the ability to convince him to do anything and he knows that he would love them, so much. Because they would be theirs.
But of course he can't have that.
Because the universe is unfair. She is a human and he is a timelord. He could never give her any of that, because he has too much responsibility over the universe and the laws of time. He has to outlive everyone and keep everyone safe, because if he doesn't, who will? He is the only time lord and the laws of time have to be enforced and he's the only one with enough power to do it.
And he doesn't want her to go. He doesn't want to watch her grow old and die and wither away, whilst he stays young and happy and vibrant. Except not happy because he wouldn't be, if she was that way. He can hardy bear it when she's in pain if someone's shoved past her a bit hard, or a gun has narrowly missed her or some aliens got his claws all over her. If he can't stand that, then he knows that he can't watch her grow old.
But even still, he can dream. He can watch her when she isn't looking and daydream and he can draw pictures of her in every notebook he owns, and write her name in Gallifreyan everywhere, and he can hug her and hold her close, but he will never cross the line. Because once he does there is no going back.
His heart is going to break when he loses her anyway, and he doesn't want to make it even harder.
But he knows that he loves her, and he thinks that somewhere inside- she knows it too.