Holy heck - this is the way Snarry should BE! It seems like they just don't write this kind of fic anymore. I loved everything about it, and when it was revealed that this wasn't the first time they'd had sex - whoa! And Harry, not wanting to admit how much he enjoys it so instead, tries to pass it off as rape. Sure, Harry, sure.
And like severed_lies said, that line was so absolutely perfect in showing the type of man Severus is.