Then they'll drop out. Like I said, this isn't starting until there is a plot, and if that takes a few months, then unfortunately that's what it takes. It's best not to rush things, as you said stuff happens. If you don't want to character dump, that's fine. But as for NPC characters, that's...not a thing in writing? I mean every character, whether they have bit parts or not, are going to have a human controling them, even for one or two bit parts.