Kind of riding blkyoda's coattails on the ultimate ideas, but this is one (short one) I thought of several months ago that depicts T'Challa as a villain:
What Ult. BP was Isiah Bradley, with a close origin to Red, White, and Black, but after he was used up and the formula was given to Steve Rogers to create the first "all-American" super-soldier, T'Chaka bought him (the group that makes the serum is "evil" and puts their projects on on a black market bid) and uses him as a personal guard and pawn in the super-human community?
T'Challa gets jealous of T'Chaka's (love, respect, etc.} for Black Panther and becomes the Ult. Klaw, killing T'Chaka--Wakanda Wars--and becomes the ruler of Wakanda, but in a Doom-style position.
Jealous thing is supposed to be like Hunter from Priest, Ult. version, Hunter would just be an advisor; Kasper Cole could be T'Challa's accomplice. Maybe the super-soldier serum could prolong life, so Isiah isn't aged that much, meaning T'Challa's grandfather could have bought him, creating a "legacy" of the Black Panther, while keeping him the same person throughout time, like biting off of Bucky from 616 (but not biting).
