He'd be lying if he claimed it didn't hurt, but it hurt less with the knowledge that Karel never went easy on him with anything. Just like his movements and sword strokes on the practice field were swift and blunt, so were his thrusts as he pressed Guy further into the bedroll, biting at his shoulders and yanking at his hair every so often.
And of course, the pain didn't mean anything in the grand scheme of things. After all, Karel was having sex with him. That alone more than made up for it. And of course there was Karel's skillful manipulation of every inch of his body, calloused but nimble fingers stroking his aching cock, the harsh nip of the man's teeth against his skin...he was rough, but so very precise in the way he worked.
"Oh God," he gasped, "this is great, it's wonderful, it really is! You're just so-"
"Quiet." Karel bit down on his shoulder, harder than before. "And stop moving around so much, or else next time I'm going to have to bind and gag you." The idea of this excited Guy all the more and even as he fell silent he hoped Karel would do that anyway.
"You enjoy this too much," Karel continued as he began to thrust harder. "You like it when I hurt you." Guy couldn't answer even if he wanted to as he began to reach his peak, sinking his teeth into the pillow to avoid screaming. Karel released inside him moments later.
"Of course I do," Guy gasped as the sensation faded. "If you didn't hurt me I might as well be having sex with someone else."
"Hm." Karel pulled himself out, running a finger along the bruise that now marked his student's flesh. "Such strength..."
"Thanks, master! I-"
"Don't talk," Karel said, cutting him off sharply. "Go to sleep. Tomorrow's lesson begins at dawn."
"'night, master," Guy mumbled as he pulled the covers around himself, already thinking up the excuse he'd give the healers this time when they saw his bruises.