sanguine, adj
The regenerator runs over the lashes criss-crossing his back, and he almost tells Cain to stop, to leave them. McCoy would never let that happen, and Malcolm sees that this is for the best. There is recovery, after. There always is. There always will be. At least in Cain's hands.
What it means, in some strange and roundabout fashion, is that he will always recover, even if it takes a long time. He will recover from his guilt over actions he could do nothing to prevent, and every little session with Cain makes him prepared to face the world. Perhaps they--he--will stop requiring this, this cycle of penance and absolution.
Cain asks if this is what he needed, voice soothing, and Malcolm cracks a tired smile.