All right, you know that this isn't my typical pairing, but this was such an enjoyable read.
For one thing, there were so many humorous details, like this one:
"It's like a date," Ron said, "Except not with someone nice."
LOL!
And Snape's sarcastic kissing? That's brilliant! Really, even the title is clever, hinting at both the "friends with benefits" arrangement that Harry had been overlooking in his own home and the one he's begun with Snape by the end of the fic.
I really enjoyed the characterizations, and the way in which you touched on canon issues between the characters was really moving:
"You know, Professor, I tried that the last time," Harry said slowly. "I let you give me what I needed, and I let you die. I don't think I could live with myself if I did that again."
There were also some really gorgeous and detailed descriptions, like this one that immediately followed:
Though Snape's hair was already lank again, Harry pushed it away from his face. It wasn't long, sweet-smelling hair. Snape's eyes didn't shine adoringly up at him or anything like that--he was still taller than Harry, a beaky man with bushy eyebrows. He would never be a pretty girl, but he could kiss so that Harry felt that he was the only real thing in the world, so that Harry's consciousness shrunk to his body where it touched Snape's: at the fluent tongue, the soft, thin lips, the arms, like tensile metal bands around his body.