Picture this: in a story, you have a character. They have a well-thought-out background story, a hardened goal to reach, surprising character development, and an overall influence on the story that makes them a well-established character from beginning to end. Now the next arc or sequel of the story begins, and the well-established character is there of course, fleshed out and everything. Only this time, they're not alone. Their sibling enters the picture. Wait, what?