I remember awhileback b4 bbs speculation got popular everybody was talking about something called a Dissoul??? This is another possibility. Idr how we said they were created but maybe when someone unlocks there heart, like MX (or ME) maybe the Soul can't pass on. So it reanimates the body. Like a nobody but different because perhaps the body takes on the appearance of the soul. In MX's case it mite look like his younger self. IDK just a random idea. Don't freak out about it. lol
It sounds like it would work actually.