u/JackInHoodZ

Tappei stated that Reinhard's POV of Arc 1 is a spoiler and given the fact that Reinhard instinctively grabbed the hilt of the Dragon Sword proving Subaru is worthy, would it be a stretch to say that one of Reinhard's Divine Protections gave him pseudo-precognition and that Subaru was the first person he met to somehow shatter this ability?

Kinda similar to how the Divine Protection of Sword Saint allows the user to see white lines indicating their enemies' attacks, Reinhard could see Subaru with infinite lines or invisible lines.

Seeing as Authorities > Divine Protections, some Divine Protections can't fathom Subaru and his Authority.

Given that one person can't hold an Authority and a Blessing at the same time, could forcing an Authority to Reinhard be a way to defeat him? Have the authority or witch factor corrupt his mind while stripping him of his Blessings and the favor of the world.

Could the end of series Natsuki Subaru "attain" the authority of Return By Death? What if the authority was always his, but he was incapable of accessing it before without aid?

Loops and Checkpoints from Al, the ability to affect memories from Gluttony, the ability to see allies', or in this case, "Beloved", status and location from Greed, compression of information from loops from Melancholy, negation of death from Vainglory, and others.

All of these are something Return by Death was capable of doing with the aid of the Witch. Placing checkpoints on people during the final conflict, tracking the status of his allies, and giving them the protection of his complete authority. A complete RBD would have Subaru acting a role similar to the Witch, keeping his loved ones alive.

Eventually evolving to a point where Subaru has access to the complete authority of Return by Death. This complete Return by Death would then be the key to defeating the WoE, and for him to be Human and complete.

Just a random theory I came up with on the spot.

Could Al and Flugel simply be two parts of a single person? Soul fragments of a Natsuki Subaru from the past, one preserved for the future and another left to set things in motion. One an idealized warrior and another an idealized sage. Similar to dream echidna and echidna, the original does not completely match with the original. Both people are their own being, but branched from a single seed. Explaining how Satella loved Subaru but never Flugel or Al.