Examples in literature: Lord of the Rings
Frodo complains to Gandalf that Gollum is still alive to torment and obstruct him, Gandalf foreshadows an important role that Gollum will play. When Frodo finally brings the One Ring to Mount Doom, he finds himself unable to destroy it, as it has gained power over him. Only the struggle with Gollum leads to the destruction of the ring, an event that Frodo cannot foresee.