Isaac wraps an arm around Stiles' waist the moment he starts coughing, the other coming up to rest against his chest once he's finished spitting up black goo and he slowly directs him towards the house.

"Derek... Derek isn't here. But, we'll... we'll find a way to stop it, okay?" He wipes at the bile on Stiles' chin, wiping it off on his own pants as he leads his mate to the couch. "C'mon. Sit. I'll... I'll get some water and text Deaton."