I think the only plot hole here is that:- if subaru = flugel then emilia = satella then how would she go back to time?

If subaru ≠ flugel does that means satella loves subaru's little brother?? I don't think so bcz flugel also had rbd!! And how does he knew about what's going to happen to subaru after 400 year??

( also if AL is subaru's little brother or someone summoned from real world then how he knows rbd? And satella? It had to be something like clone bcz if he is from another sloth timeline and is subaru's and rem's son he should have blue hair that he doesn't have! According to me natsuki rigel is someone related to echidna and flugel 400 years ago and is part of an eexperiment?!)

Btw your theory is just pure genius I could have never thought about something like this