Although Fishy Boopkins and Tari both treated him with love, Mario abused and treated him like a football, frequently kicking him around.
Though JubJub himself didn't seem to mind (as opposed to Boopkins himself, who would immediately summon his father if he were ever abused), both Boopkins and Tari criticized Mario for his abuse, and once he was reunited with
his father, Joe Boopkins wasted no time in punishing Mario for his actions.
He has mistaken Ghost Rider's (back of) shirt as his father, technically leading him to join the gang.
After his debut, he started to hang around with the SMG4's Gang and became part of the main cast.
Personality
Though he did not immediately know that Fishy Boopkins was his brother, he quickly grew attached to him.
Powers and Abilities
Like his brother, JubJub can scream extremely loud. However, he can still hear his brother while he is doing this, and will cease to do so if Boopkins requests him to stop.
Like his brother, he apparently has the ability to summon his dad by being in contact with water, though it was likely that his father had been looking for him at that point.
Like his brother, JubJub seems to be rather resilient, as he manages to withstand being kicked by Mario multiple times without being injured. He also presumably survived a massive explosion that was supposed to destroy Beeg SMG4.
He can play music from his mouth if he puts his hand on a record player.
JubJub can also be used as a spare tire but JubJub has also the right to reject his ability too.
Trivia
Joe Boopkins punishing Mario for bullying JubJub is similar to him punishing people for abusing Fishy Boopkins.
He was not named by his brother or his father. Instead, he came up with his name himself.
Though he did not see his dad upon first being born, JubJub seemed to know at some level who his father was.
Mario kicking him around like a football is a reference to Kyle Broflovski's behavior in earlier seasons of South Park, in which he kicks his brother Ike around like a football despite his brother's protests. However, Fishy Boopkins does not engage in this behavior himself.
He makes a similar noise when he eats that his brother Fishy Boopkins does.
Like his brother, he does not speak in subtitles, though he speaks much less often.
Though he is technically a fish, he happens to resemble a rubber duck. This is most likely why Tari adores him.
It is unknown where his body appearance came from, though it's possibly original, like Saiko Bichitaru or Tari.
