You start trying to cross it over with ANYTHING. I swear, I think there's a plotbunny infestation here!
YuGiOh: Duellistes du Vodoun
The premise: Yugioh in a possible alternate setting, with overtones of Vodoun. Several cult factions use vodoun magic against one another, their main objective being to bring their particular Loa into more prominence. The struggle between the Petro Iwa faction and the Ghede Iwa faction is particularly heated.
Dr. Facilier Baron Samedi!Kaiba. Want. Someone draw this please?
I actually am really tempted to explore this further by writing a fic but I'm already caught up with several projects (including that Persona/Borderlands 2 fic, which I need to get a move on). Also I'm worried that despite whatever research I do, I might offend someone if my attempts turn out too 'Hollywood Voodoo'.
Personal headcanon for this: Due to the mental image of Baron Samedi!Kaiba, I posit that he leads the cult faction worshipping the Ghede Iwa.
Also, headcanon insists that he serves as the horse for Baron Samedi. Said headcanon also maintains that if ships here include Kaiba/OC, then Theoris serves as Maman Brigitte's horse./shotdeadtrampled
As for the leader of the Petro Iwa cult faction...Obviously it's Yugi, dur. Or maybe Joey. That seems closer if only because red and black are part of his color motif thanks to Red Eyes. Of course going by that logic, Yugi should be in charge of the Ghede Iwa cult faction because his color motifs are black and purple....SCREW THE MOTIFS WE HAVE BARON SAMEDI!KAIBA.