Edit
Collection: I'm sorry it had to be this way...
Pool showing two or more characters with at least one of them taking the sadistic choice by either inflicting or in the act of inflicting a fatal wound to the other(s) (often as a coup de grâce to spare them from further suffering, transformation into a monster, etc). They must have a look full of regret and pain implying that they're doing the deed unwillingly.
Take the first post as a example.