Talk:Wasp (SF2)/@comment-31917581-20170509202142/@comment-25669516-20170510065858

I have personally always maintained this theory: the demons were normal human beings, with normal lives. When the Gates of Shadows are opened, the shadow energy that gets released ends up infecting and corrupting them. Some like Butcher were already evil but after gaining Shadow energy they become even more ruthless. (I guess I watched too much Supernatural as a kid xD)

The game does not say how the demons came to be but we know they did not exist before the Gates were opened. There are infinite explanations for that but like Anon said, it is safe to assume they were normal humans who got turned into demons due to some influence of Titan and the Shadow energy.