Post an anime character who you assumed was going to be a main character but turns out to either die or fade into the background.

yukari sakuragi(another)............she seemed to be with izumi and teshigawara always! but she died quickly!like in 3p 3 or somethin'......

The Writer from Fairy Tail (episode 49). I really thought that he would become a villain or at least a person for whoever the next villain is to use against Lucy. He had a great setup with her and the character design they used would have really made a great psychological threat for Lucy. And then the episode ends, he and Cana get together, and we never see him again. Congrats, guys. Great waste of an awesome villain setup.