[Noctis]

Originally Posted by Paul

Spoiler!

I don't really have any good guesses at the moment but since all 3 are connected, if Juvia hurts herself, won't it her the other girl as well?

Though... knowing this series, never know, she might just do something completely stupid like day dream hardcore style about her life with Gray which causes a mental meltdown for the enemy.

Spoiler!

It would also hurt Gray, so she wouldn't hurt herself to hurt the girl. I can see her beating the girl through something as dumb as daydreaming hardcore about her and Gray though.