I think the bigger question is have any MAJOR
characters died off screen? As far as i know, all major characters to have died so far have died "on screen"-Tommy,
Angel,
Kalani,
Most secondary characters (people that have speaking roles but seem to exist solely to serve a function that advances the plot in one way or another, not to be a main character) have also died on screen-Bill,
Durai,
Latch,
Samantha, Pippen,
Bricks, etc.
Of those that haven't died on screen, such as
Gatekeeper,
Bixby, and
Marcus, we are at least informed of their deaths.
So far, every time it has been implied that a main character has died, Such as
Burt and Angel at the end of
season 2, we find out what happened to them.
I seriously doubt we've heard the last of
Kelly and
Pegs. Whereas in a real life apocalyptic scenario its entirely plausible that someone could just disappear and you would never learn what happened to them, in a story like this I just can't see losing two main characters like that. This isn't real life, it's an audio drama. Not finding out the fate of Kelly and Pegs is just one big slow burn of a cliffhanger that will eventually be resolved.
Bookmarks