Some players unexpectedly need to leave early. Some players arrive to sessions late (even when using Gamer Time). Some players just don't show up at all. When the other players want to keep on playing, the absent player's character is... just there. Doing nothing. Also, completely ignored by the enemies. Kinda like they just got thrown into hammer space. Some lucky players find that they need to leave for completely legit reasons... right when they're about to die in combat. >_>