The Player vs DM attitude

[Dannyalcatraz]

In the real world, psychopaths are very good at pretending to be normal. All these interviews you see afterward where the neighbour says, "It's funny, he didn't seem like an axe-wielding maniac when I spoke to him over the fence. And he was great with the kids."

And in a medieval or FRPG world, the next sentence was probably like: "But when those brigands raided the town, he showed EVERYONE what he could do! If we had a dozen more like him..."