Derek rumbles a warning growl under his breath as Stiles starts to argue, because god dammit why can't he just accept that he has physical limitations? The growl fades out into a more satisfied rumble when Stile simply stops, mid-sentence as black veins start snaking up Derek's arm from where he's touching Stiles. He can feel the pain being absorbed into his system, his healing dealing with it as quickly as it does his own hurts. More importantly, he can smell the shift in Stiles' scent, the sour tinge of pain fading into the background.

"Yes, Stiles, I'm doing a thing," he answers, deadpan, and rolls his eyes. "And no, being human doesn't make you any less," he adds, while he possibly has the upper hand. "But it does make you more breakable, and it's my job to keep you from ending up broken beyond repair." There's something solemn and intense in the way he says it, the way he reaches across with his free hand to squeeze Stiles' wrist.