When the fight scene starts during the quest, and the opposing gang leader offers to pay you to switch side, and you accept, this gang will still be the one to be expelled out of town if you win the fight. I have never lost that kind of fight yet so I don't know what happens in this case. A possible explanation might also be that the gang leader paying me actually died - they'd always go down in fights because of them being in front of their men. However they are marked as "wounded" and not "dead" on the end of battle report.

