User blog comment:FairyRaven/Fairy Tail Chapter 392: You Must Not Forget, Review and Commentary/@comment-7418318-20140711094725/@comment-7418318-20140711174116

To torment the victim.

It's a lot like Tantalus' torment in the greek mythology, who was cursed to stand in water with fruits above his head, both of which would draw away from his hands, leaving him forever hungry and thirsty with the things he craved just out of reach.

Being granted such small freedoms makes sure the victims don't forget what it feels like to be free, but at the same time this true freedom remains beyond their reach, forever tempting and thus intensifying their suffering.