Barty Crouch Jr. (Book Version)

Bartemius "Barty" Crouch, Jr. (gone undercover as Dark Wizard hunter Alastor "Mad-Eye" Moody) is the main antagonist of the fourth Harry Potter book, Harry Potter and the Goblet of Fire. He is a Dark Wizard and an infamous Death Eater.

He spends most of the story disguising himself as the friendly teacher Alastor "Mad-Eye" Moody and became the Defense Against the Dark Arts (D.A.D.A.) teacher at Hogwarts School for Witchcraft and Wizardry during the Triwizard Tournament, hosted by Hogwarts. He was sent by Lord Voldemort, the most powerful of all Dark Wizards and leader of the Death Eaters, to fix the Triwizard Tournament so that Harry Potter wins the tournament and use his blood to give Voldemort a new body.

Why is he rejected?

 * he is insecure and played for sympathy at times