Oh, I really like this. It has some of my bullet-proof kinks:
Harry not realising he likes men, Harry's first time; Harry loving kissing;
"A blowjob, Harry."
"Yeah, right," Harry said. "Like people really do that."
... Harry being clueless; :D
Snape (having) tremendous self-control, except sometimes when he didn't.;
and finally
"Because I don't even like you." Snape's spine slowly relaxed into the curve of Harry's torso, making spoons, and he exhaled through his nose, a contented sound. "I don't."