Reavers and wardens.
I played a support warden during a time when a certain drow was the nightreaver.
1) Our first meeting was a "tense conversation" about what being in outlander is.
2) He tried to kill me in our second meeting.
3) We actively hunted an "enemy of the cabal" together. Basically you trust or you don't.
If he had tried to just kill me you would know that he is an untrustworthy twag.
4) I got between him and some fortress mages once (active healing etc).
5) He tried to kill me. :)
6) I saved him from paladins and tribunals trying to kill his ass on the galadon roundabout.
I got an "oh my" response in the immortal comments but this was never an issue for the character. This is the only tut tut that I got. For me it was simply "an enemy" is trying to kill an outlander.
7) He tried to kill me.
I never tried to kill him because, well, that was never going to happen unless I broke role and alignment to do it with others.
8) He never got me.
The bottom line was, I trusted the player behind this character to adhere to his role. Which he did. This was in essence, if there were no other enemies of the cabal to war against I was a "possible" target to hit. We spoke shit to each other more though.