the whole devil forgemaster plot of cod would actually serve as a nice template for iga's new universe. of course he wouldnt be able to call them devil forgemasters, but anti-hero(s) that betray dracula or an original vampire lord would be a good place to start imo
start a nice simple bloodfued origin story that way, "i once was in league with dracula but when he killed my family, i renounced him & my lineage will forever make sure he wont take over earth"