I hope i'm the first with this theory. I think, yes, it might be unique.
I'll give you this dialogue thanks to the latest Arc 5 Translation :
[Emilia : Emilia: My eyes, my voice, my silver hair! All of those came from my favorite person, from the most beautiful person in the world! Treating them as though they’re dirty infuriates me!]
[Sirius: Fury!? Did you just say fury!? Don’t kid with me! Fury is mine! It’s the precious thing that I received from that person! This duty and the name are all gifts from that person! To, without authorization, without permission, take that away from me...I won’t allow it! Won't, won't, won't, won't, won't, won't, won't, won't, won't, won't, won't, won't, won't, won't, won't, won't, won’t!]
Okay, so my theory is : Could it be that Flugel is in actuality Emilia's father?
Well, Petelgeuse apologized towards Flugel when he took his bones to absorb the Witch Genes of Sloth. Now that's funny, since Flugel is actually the only person we know had Witch Genes in the story formerly. So that means, could it be he also had Wrath genes?
Emilia mentions that she got her aspects of the Witch thanks to her mother/father. Let's take 'father' for this theory.
Sirius mentions that she got her 'fury' from 'that one' person. Now this actually fits pretty well. Now i'm not saying that Fortuna had the genes before the fall and Permafrost of Elior. What i'm thinking is that Crazy Geuse remembered where the 'last genes' we're hidden and showed that to Pandora. Pandora got interested into that and resurrected Fortuna and gave her the Genes, without Fortuna knowing that Pandora gave her the Genes, and still thinking that Flugel was the one that hided and had the Wrath Genes.
Please, don't be rough on me. If something isn't right, don't hurt me.