Supergirl: Ranking Every Character From Worst To Best
5. Mon-El
If you want to see a strong example of character development, then look no further than the case of Mon-El.
Originally the selfish Prince of Daxam, the character arrived on Earth oblivious to how normal people actually behaved, as he soon learned that not everyone would be tending to his own needs or falling head over heels in love with him because of his royalty. And it was a hard transition for him, as he remained selfish and arrogant, while refusing to take anything seriously. That is, until he did something he had never done before: Fall in love.
His admiration of Kara's heroism soon evolved into love itself, which ultimately inspired him to be a better person all-round as he became the hero that Supergirl herself knew he was capable of being. And this ultimately set the stage for him to become one of the greatest heroes the future had ever known.
During his time on the show, Mon-El evolved from a self-obsessed prince who cared about nothing and rubbed everyone up the wrong way into an esteemed superhero who refused to betray his wife's trust in spite of falling for somebody else. Now that's how you pull off character development.
It's just a shame that we can no longer continue to watch him develop.