Gently building off this - I'm going to guess this is based on the reality from which characters were pulled, so say, for CR AU their prior reality isn't their true origin point, but stability from a misplaced timeline would mean "from where they were originally taken by the portal?"

Noting that I don't mind and would actually love that for reasons of "why will your character stay" - if with CR AU the only reality that's easy to get back to is the one you just left, and not your true originating reality. Is that something okay to run with (on a case by case basis or otherwise)?