Jack loves to play pranks and has a devilish temperament that he never hides. He usually helps Veuve Elizabeth's clothing brand "Rougelian" and is also its image model. His favorite things are sweets and games.

Jack seems very childish and likes to tease others. He likes having attention.

When Jack is jealous, he'll take an extra step to get rid of what he's jealous of or at least satisfy himself by doing what he thinks is best to be better than the person/thing that is better than him.