Creation: In ToonKing2 fan comics Bowser Jr is Bowser's oldest son. Bowser Jr. is almost like a clone of Bowser.
Relatives: Bowser, Ludwig, Roy, Morton, Wendy, Lemmy, Iggy, and Larry.
Mother: Clawdia Koopa
Brother: Broser Koppa
Uncle:Morton Koopa Sr(deceased)
Aunt: Lemmla Koopa
Grandfather: Igser Koopa Jr.
Grandmother: Ludwinda Koopa (deceased)
Ancient relative: Ser Koopa
Relationship with Bowser:
Bowser Jr is spoiled rotten by his father. He follows in the footsteps in being bad just like his dad.
Relationship with Koopalings:
Bowser Jr obviously outranks and bosses around the koopalings. The Koopalings are jealous of him so they bully him. The koopalings Bowser Jr gets along with the most are the twins Lemmy and Iggy. The koopaling Bowser Jr argues with he most is probally Ludwig. Same thing happens in the Toonking2 Fan Comics.
Bowser Jr., alongside Mario and Princess Peach, work in team to defeat Bat Slayer Bowser in his palace, with an high tower at the top.
Bowser Jr. will appear in Super Mario Moose as a boss. He will appear at the end of 3 different worlds on his airship.
Bowser Jr. will appear in Bowser's Story as a playable character.
Bowser Jr. has been confirmed to appear in Runner Collection as a boss. His attacks are currently unknown.