Of course he knows how she feels about him. It would take an idiot not to notice, there's no way a ninja with his skills could miss the signs. The blushes whenever he so much as looks in her direction, the furtive little glances when she thinks he's not looking, how she stammers when she talks to him.

At first it was an irritation, yet another idiotic girl vying for his attention. He made a point of ignoring her whenever possible; dispelling any hope she might have that he would return her affection. He fully expected her to be bored of him in a week, and it was true she stopped actively pursuing him, but the little signs remain. He can't understand it, she knows she has no chance with him, yet her feelings get stronger, if anything.

He decides she must be very stupid, yet under the surface he has a grudging respect for her blind, unconditional love for him. The way she can be blindly faithful in his abilities one minute, and convinced he has been killed by the most infantile of tricks the next. Their shared disdain for their irritating team mate.

But he cannot love her in return, because he has to kill his brother and cannot be distracted, because it would cause yet more conflict between himself and Naruto, because it would complicate the dynamic of the team, because she is utterly useless in battle, because she's so damn optimistic for no good reason, because she seems so docile yet he can sense the frustrated undercurrent that runs beneath the surface and he cannot waste his time trying to figure her out because what good would that do him in the end?

So he'll continue to ignore her unless the situation calls, and if he praises her it is because she needs encouragement to become stronger, and he needs a strong team to back him up. And when she screams his name in battle, he'll pretend it doesn't give him the strength to carry on.