User blog comment:FairyRaven/Fairy Tail Chapter 390: The Story of a Boy, Review and Commentary/@comment-117.195.32.112-20140627092139/@comment-4829046-20140627093859

Actually fragments of memories and traits can remain in the body(weren't the ones under Zoldeo's human subordination dead? If they weren't then, they are now anyway), plus considering what happened to Jellal, it isn't that unbelievable. It is also possible that despite the body being dead, his soul was still there and merged with Deliora when he took over the corpse.

Capricorn's magic isn't really specified other than being a combat butler.