Fan Casting Breakout Character in Sort by Tropes

What's a writer to do when a minor character that they created for a show suddenly becomes much more popular than the other members of the cast? Why, re-write them as a main character, of course! This is that character. Usually starring in a sitcom, the breakout character quickly grabs hold of the audience's attention and writers take advantage of this energy. Someone who was once a one-note C-character, such as a Satellite Character or a Living Prop, becomes a central part of the regular cast. Often liable to lead to a Spin-Off, or be subject to becoming an Adaptational Badass.