Maybe a thoroughly corrupted faction could even start having that god's lesser demons in their armies, or have an Exalted Greater Demon become a lord, showing their utter control and integration? Of course this would make them just as hated as the demons, if not more so! Build up your specific corruption enough, and you can sway the faction leader to follow your designs.
I would honestly hope for that, but just with Chaos, perhaps with all the Gods but Khorne, or maybe just Slaanesh.
Get it high enough, and you could just straight-up vassalize them, making pitiful mortals into your eager-to-serve thralls. The more Vampire Corruption in a faction's land, the more likely they are to listen to a vampire's diplomacy. I made a video a while ago discussing a rework for Corruption across the game, and one of the big ideas I had was making the 'Vampiric Influence' diplomacy trait actually mean something.
