Apocalyse's soul didn't posess him, he was inverted by the spell. Apocalyse is something that's always been a part of Evan but he tries to be better than that part of him so not to succumb to it. The spell however brought that side of him to the surface causing him to become this way.
I don't want Evan, Dark Angel, Weapon Omega or any other fakers. There is only one:
I think I'm over Apocalypse. I think there are a couple of villains and superhero tropes (such as hero vs. hero fights) that just need to be benched for a long time.