When I choose to summon the naked halfling, at first he and his summoned demon help out. But once the enemies are slain, he turns on me. Is this normal? I don't remember it being that way on my last playthrough. Maybe it's because I'm evil?
My guess is that you or your followers are somehow damaging him and/or his demon, setting them hostile in result. Sometimes happens in the heat of battle. Since he's not technically a follower, some normally safe means of dealing damage (for example grenades or Jolt) can be the source of friendly fire in this case.
That is a plausible theory, but no, I think they both just go hostile at combat's end. I disbanded all followers except my summoned ogre, and just went melee only. They still attack as soon as all other enemies are dead. Damned inconvenient. Is everybody quite sure that Arcanum Edit does not interfere with or corrupt the UAP? I have had more than one instance of strange behavior in this game, since editing my character.
How does Angelie behave when you summon him outside of combat? How high is his reaction towards your character? Also, what other strange behaviour in the game have you experienced?
Angelie being the name of the aforementioned halfling? Outside combat, he behaves normally, meaning he just stands there neutrally. After a bit of testing, I think he just doesn't like either my ogre or Geoffrey. I would have to do more testing to discover which, but I strong suspect it's the ogre because of his nature. I will have to start taking notes, I never remember past issues. I just remember a half dozen eyebrow-raising behaviors I wasn't used to from the game, that I thought might be bugs.
Ok here's the next one I happened to notice: in the hands of Geoffrey, the Staff of Healing has unlimited charges. It is stuck at 19 remaining, down from 20, and will not drop below that in spite of the fact that he uses it constantly.
