User blog comment:Iron.Shadow.Dragon/Take Over: Satan Soul origins?/@comment-24066070-20131020112631

Elfman can just copy something by touching, as he did with Rusty Rose's arm. So likely the TO of his sisters works like that as well. So perhaps Mira encountered some demons in her youth or while on a mission. I think Hades once said Zeref created "tens of thousands of demons" (although this is probably just some figure of speech). At least Zeref created a lot of them, so it might not be that strange to encounter a few. I just hope Mirajane won't be able to copy those Demon Gates, would be a bit overkill if she obtained their powers.