Something I didn't mention when the #P1e #Ustalav party dealt with demons last year is that the #tiefling bloodrager was #possessed by a #dretch #demon. (They can't normally possess, but all #demons have some form of #possession in my campaign.)
It can't control the bloodrager's actions, but can manifest from her and retreat back into her at-will, until it leaves voluntarily or is expelled. It's been a minor nuisance so far but is escalating.