Born in La Push, Washington
Born to Billy and Sarah Black, Jacob is a member of the Quileute tribe in La Push, Washington. Jacob's mother died in a car accident when he was only nine years old. His two older sisters, Rachel and Rebecca left home soon after the accident. Rachel, his oldest sister, married Solomon Finau and moved to Hawaii. His other sister, Rebecca, went away to college. After her graduation, she returns to La Push and is imprinted on by Jacob's friend, Paul Lahote. Because his sisters were away, Jacob cares for his disabled father, Billy, and they become very close.
Jacob rekindles his friendship with his childhood friend, Bella Swan, when she returns to Forks to live with her father, Charlie Swan. Billy and Charlie have been friends since childhood themselves. Jacob is the one who first tells Bella about the "cold ones", the vampires. He also tells her about the legend of the Quileute tribe; how they can shape-shift, or become wolves. According to legend, they only phase when the cold ones are near. Jacob doesn't actually believe the legends; he thinks it's all just superstitions. But when Jacob's friends distance themselves from him and fall under the influence of Sam Uley, a young man from their tribe, Jacob becomes frightened.
Soon he's experiencing mood changes, anger, and a high body temperature. Jacob phases into a wolf for the first time when he's sixteen years old. He then learns that Sam is the leader of his "wolf pack".
Jacob and Bella grow very close, especially when her vampire boyfriend, Edward Cullen, leaves her. Jacob's love for Bella grows, but she never truly returns his love. When she later marries Edward, they have a daughter, Renesmee Carlie Cullen, who Jacob imprints on.
Just before Renesmee is born, Jacob forms his own wolf pack, as he is the great-grandson of Ephraim Black. He is the largest of both packs, and he is the second fastest behind Leah Clearwater.