He's shown to have kleptomaniac tendencies, as he often steals objects on the fly.
Like the others, Jay was never shown affection by his parent so, when he tries out for the tourney team and makes it, he gets a chance to see what's it like to be a part of something as special.
By the end of the film, he is determined to become good though he has yet to fully give up his kleptomaniac ways.
In addition, he seems to retain his tough confrontational attitude and will get into fights with those who anger him, such as with Carlos in episode 10 of Wicked World.
He has dark chocolate eyes, that could charm anyone especially the girls. In the Descendants film, he is shown during the song Rotten to the Core stealing items and causing havoc with his friends.
In the novel Return to the Isle of the Lost, he displays a mild-tempered and smart exterior, as he takes Chad's assault with stride and manages to keep his greed from taking over when confronting the Golden Cobra.
Jay is described as a boy with long hair who's muscular.