And he still claims not to be the wise sage Flugel.. Shaula legit either has to be his disciple and that means he was actually Flugel before somehow, probably with some timey-whimey doohickery, or the all-knowing sage created all of this with Subaru In mind; for example planting the tree specifically to later let Subaru use it to kill the white whale.. Or they're just also from Earth.
Either way I'm leaning towards Subaru just straight up being Flugel because Shaula has his black and orange color scheme, vaguely acts and talks like him, pretty much immediately recognizes him via the witch miasma smell(?), the first test was based on a constellation from Earth which Subaru just happened to know the story of (I haven't even ever heart of 'Asterism' before let alone Orion getting his ass handed to him by a scorpion).. The conveniently placed tree used to kill the White Whale..
Subaru just straight up is Flugel.
I don't know how else you'd explain this.
Anime only btw