Wolf saw Felix's lips moving, and he understood what he was saying (complimenting his tennis game), but his mind wasn't focused on that. Instead, he was thinking about how Felix was looking at him, how he wasn't moving away from him or attempting to put space between them. The guy was squirming instead, but not in a way that Wolf got the feeling he wanted to split. Felix didn't seem like the type of guy to put up with that from another dude if he didn't want it, even if he didn't want to admit he wanted it.
Honestly, it was a surprise. Wolf wasn't even entirely sure he was reading Felix correctly or if all of the signals he was picking up was wishful thinking. He hadn't had a lustful eye on Felix or anything, and he hadn't been crushing on him (it had been a long time since Wolf had harbored a crush on anyone), but who could blame him for wanting to engage in more than talking with an attractive person while they were all alone in his room? He was sure someone could, but Wolf wouldn't blame himself for it.
As a test, Wolf lifted the hand still holding the bottle cap to pull at the neck of his pink button down shirt. The top few buttons were left open, and Wolf acted as though he were casually rearranging the neckline just to see if he could attract Felix's eyes to his collarbone. It was exhilarating to think of the situation he might have unwittingly found himself in. Felix Ruskin, he never would have known, and he was close friends with Luke. How men in denial stuck together! It was funny, and Wolf couldn't keep the smile off his face.
"That's why I chose tennis. I could have gone for other sports, but tennis is my favorite." At that point, Wolf was only replying to Felix so awkwardness wouldn't permeate the moment. Awkward silences were somewhat beyond his realm of understanding, but he had been socializing long enough to know how his fellow teens got restless when someone's mouth wasn't flapping.
Nonetheless, Wolf's real focus was on his own hand, which had left his collar to press against the soft fabric of Felix's sweater with force, meaning to pin him against the door. The gentleness of the gesture, despite the deliberate power behind it, might have at first seemed as though it were a thoughtful way to give Felix an easy out if he wasn't totally enamored with the arrangement, but that wasn't it. Wolf just didn't want to freak Felix out before he had the chance to do what he was doing now: leaning forward to cover Felix's mouth with his own.