Pavlovian
"Well you know what? It doesn't help that you- um," Blaine stops in the middle of his angry sentence, and Kurt blushes because he knows exactly what Blaine's looking at.
"Please don't," Kurt groans.
Blaine presses his lips together. He can't focus on his previous anger. What was he yelling about again?
"Really, though?"
Kurt turns around and marches to the couch.
"That's like, level five boner and I haven't said anything sexual at all."
"Ugh!" Kurt throws himself onto the couch. "You know it's your fault. Make-up sex is so great! Yeah, until I develop a damned Pavlovian response to arguing with you. This is so embarrassing!"
Trying very, very hard to choke back a laugh, Blaine sits next to Kurt, on the edge of the couch. "At least we're no longer arguing," he says, bringing his hand to stroke Kurt's bicep. "I can't even remember what we were arguing about, to be honest."
Kurt nods. "I can't, either. It was a stupid argument."
"Yeah." He waits a beat before asking, "So no make-up sex?"
Blaine barely has time to blink before a pillow hits him square in his smug expression.