Billy Black is a direct descendant of Ephraim Black, the last chief of the Quileute Indians. He’s best friends with Charlie Swan, Bella’s father. When an illness leaves Billy confined to a wheelchair, Charlie buys Billy's old Ford truck for Bella. This is how Bella meets Jacob in Twilight, and how she comes to learn the Quileute legends about vampires and werewolves, and the fragile treaty of peace between them.
As one of the tribal elders, Billy considers vampires his natural enemies. He tells Bella from the beginning to break up with Edward.
When his son Jacob turns into a werewolf, Billy tries hard to keep Bella away from him. Once Bella discovers Jacob’s secret, though, and Billy learns about the danger the vampire Victoria poses to Bella, he helps keep Charlie and Bella in La Push, to protect them and to support Bella’s relationship with Jacob.