IIRC, there was a Tribunal a couple years back that got kicked out of the cabal and ultimately turned neutral and maybe eventually chaotic (I don't remember) for consistently behaving like a psycho. I remember feeling like it was more the player coming off their hinges than genuine, deliberate RP, but nonetheless the needle moved accordingly.

Beyond that, if it has happened it's certainly uncommon. That said, if a character doesn't seem to fit their ethos that may impact various Immortal's opinions of them, the outcome of role contests, etc.