Wyll can become permanently stuck in character's party, trapped in his state of not having been accepted into the party yet but still acting as a party member even going so far as to have companion quest conversations still
This bug occured after Killing Kahga (or whatever her name is, the aggressive Archdruid woman)


Wyll may become stuck permanently in party after Wyll enables a conversation mid area-transition after his NPC AI bugged out post-important event at the Druid's Grove and wandered away of his own free will into an area transition.
This bug may affect other companions