Don't worry about it. Stein and Mia are over the standard border of brutality and horror. When I make overly powerful or dangerous characters, I usually don't make them so they'll attack everything on sight. Mia and Stein are ridiculously dangerous, I mean, as of yet neither has gone full-power against anyone, and they'll torture your character and maim them without a problem. They are SERIOUSLY brutal.
As such, I'll never force anyone to interact with them. It's an at-your-own-risk situation.