User blog comment:FairyRaven/Fairy Tail Chapter 390: The Story of a Boy, Review and Commentary/@comment-117.195.32.112-20140627092139/@comment-4829046-20140627100349

Actually that first part depends on author. Some keep it so that the person IS dead/possessed but can still think and retains overall personality prior to death/possession while in other cases you only reactivate the body(zombie) Naruto mixes both these elements.

There doesn't necessarily need to be regret for it to remain around the body, outside forces can also interfere according to circumstances and individual so the mother's body doesn't need that trail of thought really.

With Jellal, his body was overloaded with magic so he was in a suspended state, neither really live nor dead, requiring Wendy to stabilize it. HOLD ON A SEC!!!! Could that mean Wendy is needed to weaken Silver?! O_O I highly doubt it and it sounds crazy but if the theory holds, and Doranbolt uses his magic, then Wendy could do something that makes Silver's body have conflict with itself between the original Silver and Deliora, allowing them to destroy it. Just a crazy idea.