I was working on a fic where a Batman is forced to work with a vigilante who is determined to hunt down a psychopath who killed her son. Bats gives her an ultimatum that is she is to work with him she will stop herself from killing at all costs. She agrees - and then proceeds to maim all four of his limbs, and then paralyzes him so his brain and sight are fully intact, but he will never be able to move more than his eyeballs ever again. And when Bats finds him, the mutilated criminal is begging with his eyes to put him out of his misery. And Batman can't make himself grant him that final mercy because he has vowed never to take a life.
...
What? He killed children; it's totally justified. *is evil sociopath*