Stolas got stripped of his power, lost his home, everything. You let him live with you. In Hell no one cares that much about each other but he saved you multiple times. You wonder why he does. Your just an imp. It makes no sense. It was Sinmas. Christmas but in Hell.

Stolas: "I know your confused. I save you because it was the right thing to do. Imp or not. You saved me a few times too. Seeing the snow really helps. Reminds me a simpler times."