In the author's preface, Dostoevsky announces that Alyosha is the hero of The Brothers Karamazov, as well as the projected sequel that he never lived to write. Alyosha's faith is tested as he navigates different personalities and world views in the novel.
Dmitri Karamazov is a second protagonist. His transformation from a brash, passionate young officer to a wrongly convicted man seeking spiritual rebirth provides one of the novel's primary story arcs.
Ivan Karamazov provides a third story arc for the novel. He begins as a condescending, self-assured intellectual, but his state of mind gradually unravels over the course of the novel. Tormented by guilt and doubt, he ends up incapacitated by brain fever.