Introduce in via DLC or in the next game. Id buy it. Maybe the Darkness takes control of Cayde-6. He is already kinda a comic relief dude. Now just imbue him with darkness, and make his humor more dark and weird. Tah dah. Something like that? Id buy it. One part of the DLC is him fleeing on a diamond looking sparrow, and if you get up close and freeze the frame, you see buttstallion scribbled on the side. And for an angel/maya/lilith substitute, a darkness infested ikora rey? Shes a warlock, they are kinda siren-y? Shaxx/Zavala/Saladbin gets a taste of it too, but not to make him evil, just a lil crazy. Booom, gunzerker/brick/torgue. Tex mechina or whatever its spelled, maybe turn her into a scooter/guage/tiny tina person? I think this would be fun.