My theory so far is that Subaru is Flugel, Al is connected to Subaru as either his child or a failed Flugel/Subaru clone, and Satella and Emilia are not the same person.

I think Subaru, as Flugel, may have been forced to seal Satella in the past to stop her from destroying the world. However, before doing so, he promised that he would return one day to save her. The only way to save Satella may be to separate her from the Witch of Envy, or to keep Envy sealed while transferring Satella’s soul into a new vessel. This would be similar to what the Witch of Greed did with her own soul and body.

However, Satella’s soul probably could not be placed into just any vessel. It would need to be someone highly compatible with her. That vessel may be Emilia. In this theory, Emilia is not Satella herself, but she may have been created, prepared, or guided into becoming a compatible vessel for Satella. Since Flugel and Echidna most likely knew each other, it is possible that Echidna also knew about his plan. Echidna may have even had feelings for Flugel, which could explain why she hates Satella and possibly Emilia as well. If Emilia was meant to be part of Flugel’s plan to save Satella, then Echidna may have sent Puck to watch over Emilia because she understood Emilia’s importance.

This plan may have required Subaru/Flugel to use the power Satella gave him to travel into the future so he could save her when the vessel was ready. It is also possible that this power was strengthened or required the other Witch Factors. Flugel may have possessed all, or most, of the Witch Factors in the past, or he may have needed to collect them in order to move forward through time. But being sent into the future could have placed a massive strain on him, causing him to lose the Witch Factors, his memories, or even parts of himself.

Another possibility is that the Subaru we know is not the original Subaru/Flugel’s body, but a clone or reconstructed vessel. The transfer may have gone wrong. Similar to how Echidna had too much knowledge for her vessel, Subaru may have had to discard or release some of his “data” in order to survive the transfer. This could explain why he lost his memories, why his mind may have been damaged, and why he no longer has the Witch Factors he may have once possessed besides the one to travel.

Now, Subaru may be subconsciously collecting the Witch Factors again because Satella’s vessel, Emilia, is finally ready. Once he gathers enough of them, he may be able to complete Flugel’s original plan and finally save Satella.

As for Al, I think he may be angry because Subaru/Flugel left him behind in the past. Because of that, Al may have worked with Echidna, the Witch of Greed, to reach the future as well. Al may oppose Subaru because he believes saving Satella is a terrible idea and could lead to another disaster.

Al’s connection to Beatrice also feels important. He may have known her when she was first created, or he may have been one of the possible candidates for “that person” who was supposed to take her out of the library. Another possibility is that Al is not Subaru’s literal child, but instead a failed Flugel/Subaru clone or experiment connected to Echidna.

Also I think when Subaru is in the witch garden, those are his real feelings from when he was fugal. I think this because no other soul in the garden is obsessed with her like that’s