Jacob is Bella's friend in the Twilight series. He plays a significant role in Bella's life, providing emotional support and friendship. Jacob is initially introduced as a childhood friend of Bella's and later becomes a crucial character in the story, particularly in the love triangle between Bella, Edward, and himself. He is part of the Quileute tribe and has a strong bond with Bella, always being there for her during her struggles and offering his friendship and protection.