
Official profiles state that Oggy and Jack are cousins, but this is never directly stated or even implied in canon, as Jack was in a romantic relationship with Oggy's twin sister, Monica. However, at times Jack's ego can get the better of him, and will sometimes antagonize Oggy, this usually ends with Oggy making peace with the cockroaches to stop Jack and give him what he deserves.

Jack can be protective of Oggy, as shown in the episodes Flower-Power and The Rise and the Fall. He almost always helps Oggy when he is in trouble, whether it is from the cockroaches, or getting stranded in space. Jack tends to be Oggy's partner in many episodes. Additionally, he had a Ferrari in The Pumpkin that Pretended to be a Ferrari. Throughout the series, he mainly has a small green monster truck-looking jeep with flame paint jobs. Jack owns an orange van that is mostly used in the episode Drone Out of Control!, he also owns a yellow safari jeep that is mostly used in Life's a Zoo. He is an olive-green cat with a pink tummy, white paws, yellow freckles, a sharp tail, and hair coming out of his ears. He tends to play the "straight-man" to Oggy and the roaches's antics. However, at times, Jack can show his nicer side when he's not focused on stopping the Cockroaches or acting villainous. He may be the easiest target in the show, mainly because his rage gets him too unfocused on either getting rid of the Cockroaches.

He sometimes bullies Oggy, either moving him when he is in front of the television, trying to beat Oggy in a race, or going insane.

Jack often builds something to try and destroy the Cockroaches, or any other insect that roams Oggy's house, and while he has had some success, most of his plans backfire. He is focused on getting rid of the Cockroaches or doing something selfish. He is quick-tempered, violent, focused, self-important, sometimes lazy, and a mechanic. Jack can be described as the opposite of Oggy.
