Bite Marks
Hibari pushed Mukuro onto the bed with a shove. He was pulled after him by his tie which was discarded moments later. He unbuttoned the other man's shirt and worked his way from his mouth to his neck. Hibari found his pulse point and bit down. Just as he was about to break skin Mukuro pulled him up for a kiss.
"No biting." He said when they stopped for air.
"Why?"
"My skin's too pale. It looks horrible."
"Just hide them with your herbivorous illusions."
"It's a waste of energy; hiding your teeth marks."
"Too bad." Hibari bit down on the same spot as before, drawing blood.
However that was the last time he did so without Mukuro's consent.