Kai (LEGO Ninjago, seasons 8-12)

Kai is one of the main 6 ninja of . He is the red ninja of fire, and Nya, the master of water's older brother. Unfortunately, during Seasons 8-12, he suffered flanderization and character derailment.

Bad Qualities (Seasons 8-12 only)

 * 1) He went from being a short-tempered and cocky yet lovable ninja to an annoying, narcissistic, whiny character who tries to be comical for no reason.
 * 2) In Season 11, he constantly berates his teacher/mentor, Master Wu, for Aspheera taking his powers away, because of Wu's history with her, when he's had his powers taken away because of Wu's history with a villain BEFORE, and they were well within volition of stopping Aspheera from coming out of the tomb after Zane warned them, as seen here.
 * 3) And while you could argue that it was because he felt like an average person without them, he still has his years of combat experience, training and Spinjitzu!
 * 4) Also, Even though he admitted he didn't need powers to be a hero at the museum, 3 episodes later that "development" got all flushed away after he found out that Wu had history with Aspheera.
 * 5) He's incredibly cocky. While he was cocky in Seasons 1-7 and Day Of The Departed, years of experience had developed him over time and it became more of a courageously cocky trait. Now, it seems as if cockiness is just his main trait, only for the sake of maintaining the status quo.
 * 6) His leadership trait (showing in scenes like his speech about stopping the Devourer without Wu in Season 1, or variously regarding Zane in Season 4) is essentially thrown into the garbage in favor of his tryhard comical attitude.
 * 7) In Season 12, he's really annoying, constantly using sarcasm to an annoying degree, and is considerably whiny.
 * 8) The scene in March Of The Oni where he randomly says "a pillow" when Lloyd tries to tell Garmadon he doesn't trust him, while not terrible, is kind of cringeworthy and would've been way more consistent with the character personalities if Jay said it.
 * 9) As said in BQ #1, he's always trying to be a comic relief character like Jay in these seasons. Not helping is the fact that Jay is actually funny.
 * 10) Addressing the elephant in the room (for Ninjago fans), in the Season 8 finale, he hesitated possibly giving up his powers to save Lloyd just because "They would need their powers to stop Garmadon", which completely goes against his character in the previous seasons, where he has a strong relationship with Lloyd and would give up  anything to protect him.

Good Qualities

 * 1) In season 13, he became a lot less childish and annoying, and became a lot more mature. He also started to actually be funny, while not trying too hard to be the comic relief character. These factors and many more returned Kai to his Season 1-7/DotD traits.
 * 2) The scene in Season 10 where Kai comforts Nya regarding Cole's "death", was a very heartwarming scene and arguably one of the best moments in the Oni trilogy.
 * 3) The scene in season 9 where he teaches young Wu a lesson about confidence could be considered good to some people.
 * 4) Following up on GQ #2, Overall, out of the 5 seasons of Kai's flanderization, Season 9 or especially Season 10 could be considered the season where he is the closest to his Season 1-7/13-present personality.
 * 5) He reforged the Golden Weapons, aiding in defending Ninjago from the Oni.
 * 6) He still defends Ninjago from threats.
 * 7) His Season 8 redesign at least has elements from his Pre-Season 8 appearance and overall works well.
 * 8) https://www.youtube.com/watch?v=w3tXD0PRmNY 1:03 onward. Nuff said.

Trivia

 * Kai's voice actor, Vincent Tong, is the same one who voices Flash Sentry from My Little Pony: Friendship is Magic.