Bowser Jr.

Bowser Jr., known as Koopa Jr. (クッパＪｒ．Kuppa Junia) in Japan, or sometimes simply called "Junior" is a secondary antagonist in the Super Mario franchise. As his name implies, he is Bowser's son, brother of the Koopalings and prince of the Koopa Kingdom, serving as the heir to his throne. He debuted in Super Mario Sunshine, and has since helped his father to kidnap Princess Peach and battle Mario and Luigi in many subsequent games. He has also taken on playable roles in spin-off titles such as Mario Superstar Baseball and Mario Strikers Charged.

Why He's Bowser's Boy

 * 1) He has a great father-son relationship with Bowser.
 * 2) He has a surprisingly cute design.
 * 3) He was a pretty good antagonist in Super Mario Sunshine and he started appearing in more games like New Super Mario Bros, and Super Mario 3D World + Bowser's Fury.
 * 4) Junior is extremely loyal to his dad despite his evil ways, and he often brings out Bowser's rarely seen emotional side by interacting with him.
 * 5) He finally makes a return in Mario Kart 8 Deluxe in the Mario Kart series.
 * 6) He's every ambitious and smart for a little kid.
 * 7) Both Delores Rogers and Caety Sagoian do great at making him sound like a scheming, mischevious little infant.
 * 8) He's always willing to get out of his way to please his dad in any way, shape or form.
 * 9) He has limits when it comes to serving Bowser. For example, in Bowser's Fury, he was going as far as teaming up with Mario to save Bowser from his Fury form and turn him back to normal.
 * 10) Speaking of his father-son relationship with Bowser, they have a lot of cute moments such as the Nintendo Switch Parental Controls video where they spend time playing the Nintendo Switch together.
 * 11) In some games he appears in, he has his signature Junior Clown Car, like in New Super Mario Bros. Wii/ U and Super Smash Bros., which is a nice reference to how Bowser uses it in his boss fight in Super Mario World.

Bad Qualities

 * 1) He can be bratty and annoying at times.
 * 2) His crying in Mario Golf: Toadstool Tour and Mario Kart: Double Dash!! when he loses can be quite irritating to listen to.
 * 3) *One of the taunts he does in Mario Kart Tour is rather weird for him to have, it's mostly an act Iggy Koopa would do as shown in New Super Mario Bros. games.
 * 4) He was unintentionally responsible for the Koopalings' flanderizations from being Bowser's children to some unidentified top-notched minions. Heck, in Super Mario Maker, he even stole Ludwig's moveset from Super Mario World.
 * 5) While this fortunately didn't ruin his character, Nintendo gave him too much spotlight and after Sunshine, with him taking part of almost every mainline and spinoff Mario games.
 * 6) Despite helping Mario in Bowser's Fury to get Bowser back to normal, he came across as ungrateful in the ending cutscene, grimacing at him after Bowser was restored.
 * 7) He had a bad (but thankfully it doesn't last for too long) franderization in his own sub-mode from Mario & Luigi: Bowser's Inside Story + Bowser Junior's Journey.