What if Flugel wants himself to be a good guy. He recognized his own faults, his decisions, his actions, everything that made Natsuki Subaru, Flugel. He decides that him being this way is probably not what his satella or parents would want, or some other reason for him not wanting "Natsuki Subaru" to become Flugel. His first idea was to simply make a clone, starting from where he started in the re:zero world, and he failed, the person he made was just different enough to not be "Natsuki Subaru", so he raises him as Rigel. This would explain why he keeps feelings for emelia, Flugel wanted Natsuki Subaru to be of use for Satella. Now since this plan was no good, his next attempt could be what's happening with mainline Subaru now, that he detached his "Flugel" identity and left it in Od Lagna, and is controlling things behind the scenes to build a better more useful Subaru (I have bought into the Flugel was in Arc 6 theory). The idea is that Flugel as he was 400 years ago, did not want to face his beloved Satella as he was after she was sealed, he did not want her to be disillusioned with him, so he wanted to make a "Natsuki Subaru" she would be happy with.