A stereotype of movies. If a character is not specifically important to the (movie, game, etc.)'s plot, or simply isn't "good enough", that character is doomed to die by the end of the story.
I'm surprised that Daniel didn't die by the end of that movie. He had a severe case of Side-Character Syndrome, after all.
by KMPeterson November 13, 2017
noun. A disease attributed to many anime side characters that are initially introduced as interesting, powerful, or popular characters that get incredibly nerfed by the plot to make the main protagonist look better by comparison.
Rock Lee and Neji used to be dope characters before they all caught Anime Side-Character Syndrome (ASS) in Naruto Shippuden.
by ChidoriSnake September 4, 2019