There's a special place where characters go when they fail to show up for the next season without a peep from the other characters. Their souls are in limbo. We pray that they find their way to the otherside but, more often than not, it does not happen. Shows end without discussing the character again. They walk the plane between life and death.
This land is called Mandyville, made popular when Mandy Hampton (Moira Kelly) disappeared without a trace after being a main character on the first season of The West Wing.