One of the most interesting concepts that the Leviathan AW actual play episodes introduced me to was making a new character in an RPG be an existing NPC. I was kind of disappointed that this idea wasn’t actually mentioned in the ApocalypseWorld text. It’s just an idea that I wouldn’t have thought of on my own, and I now associate very strongly with AW.
And it’s such a good idea! It solves the issue of playing 6 sessions, a PC dying, and that player making a new character who joins a party that has, up till that point, kept mostly to themselves, welcoming them with open arms.