Dracula is actually a misunderstood bad guy in this universe? Wow, that is terrible. I already thought of Gabriel being Dracula but I figured they wouldn't pull another Soma. But I guess not.
And how does this fit into the canon again? I still don't get it.
This is my strawhatted theory, and while ridiculous, it's only a cherry on top of the ridiculous cake.
Gabriel was never a real Belmont and only used the name as a surname (it's implied that he's a member of the Cronqvist family) so with all of the jazz going on with the game, and the fact Gabriel can't seem to be given release by being immortal, he decides to have his revenge against God by becoming a vampire, which begins the whole Mathias thing with Lament of Innocence (Lords references this game a LOT), which then just leads into the Dracula we know of based on the main IGA canon.
The strangest thing I'd find with such a silly fan-idea is that that would mean Dracula has loved 3 women and wanted to smite something for the loss of them. Surely he'd give up at some point

.
It's not as bad as the Belmonts literally being the children of Alucard, though.