Name: Jacob Black
He has a small but important role in this book. After being flirted by with Bella Swan (as a way to get information) He introduces her to the idea that Edward Cullen is a vampire by telling her Quileute legends. According to Stephenie Meyer via her official website, Jacob was originally just a device to tell Bella about the "Cold Ones". However, both she and her editor liked Jacob so very much that they decided to give him a much larger role in New Moon and Eclipse, the sequels to Twilight.
In New Moon, Jacob comes into the story when Bella Swan comes to him to fix her two motorcycles, offering him one as compensation for his repair work. He helps her, and as their friendship grows, his crush from Twilight develops into a strong love. Bella does not think of him in anyway like that because she is still mourning for Edward, who left earlier in the novel.
Jacob is one of an ancient line of werewolves, a member of the Quileute Tribe that has forever been the mortal enemy of any vampire, even the (relatively) innocent Cullen family. At first Jacob thinks all this is legend, and he is frightened and disturbed by the influence a young man on the reservation, Sam Uley, has on some of the Quileute youth. But when Jacob makes the change himself in response to a new vampire threat, he learns that Sam (leader of the pack) went through his own 'werewolven' hardships, including a rather bloody incident with his girlfriend (now fiancée) Emily. As werewolves are short-tempered, highly violent, and likely to explode into wolf form when provoked to anger, Jacob, prompted by his new pack, agrees that he should stay away from Bella. Besides, he is busy patrolling the forest with his pack, searching for the vampires in the area who are killing local hikers. Jacob and the pack save Bella, who is in the meadow Edward showed her, from a vampire. Laurent (from Twilight) catches Bella alone in the clearing while hunting and attempts to kill her. Before the over-sized wolves run him off, Laurent tells Bella that Victoria, the red-haired mate of James (also from Twilight), is trying to find her to have her revenge on Edward, who killed her mate.
During a conversation in which Jacob almost kisses Bella, Bella's phone rings. When Jacob answers the phone, he tells who he believes to be Carlisle that Charlie is "at the funeral". In reality, it was Edward pretending to be Carlisle, and thinking Bella had died (making the assumption that the funeral Jacob is referring to was Bella's as opposed to Harry Clearwater's), and he immediately goes to Italy to ask the Volturi to kill him. Bella and Alice go to find and stop Edward directly after the fateful phone call, leaving Jacob hurt and angry. Jacob is hurt and disgusted by Edward's return and by Bella's willingness to go back to him and become a vampire.
Presumably, after the Cullens and Bella return to Forks, Jacob has become their enemy because of the treaty, making Bella his enemy as well because of her refusal to leave the vampires.
The book ends with Jacob putting Bella's motorcycle in her front yard in order to get her in trouble with Charlie, so she would not be able to see Edward anymore, which angers Bella immensely. He also reminds Edward, flanked by Bella, of their treaty, in which the Cullens are not allowed to bite a human. This means that if one of the Cullens turn Bella into a vampire, the treaty is broken, and the werewolves no longer have any reason not to attack them, leaving an open plot for Eclipse.Bella says angrily that it's none of Jake's business. At the end of the meeting, Bella and Jacob (who she affectionately calls Jake) are about to hug when Edward pulls Bella back, saying that it would "not be okay." Jacob begins to shake and his body swells as he gets mad which will turn him into the werewolf. But Bella manages to calm him down and Bella and Edward leave. However, Bella's last look at Jake is of his face crumpling in emotional pain, and she vows that she will see him smile again.
The third installment of the series begins with Jacob still trying to keep a safe distance away from Bella. She desperately tries to get a hold of him to talk. But he continues to ignore her attempts. He decides to write her a note instead. He is not comfortable with the idea of Bella walking around a vampire. And the thought of it causes him to almost lose control with anger.
The book starts with Bella reading the note from Jacob. He has a hard time expressing himself in the note, as she reads through many unfinished sentences that end up being crossed out. The last comment in the note is not crossed out, and shows he is still angry with their situation.
Yeah, I miss you, too. A lot.
Doesn't change anything. Sorry.
Later on in the series, his affection towards Bella grow stronger. He's enraged by the fact that she will become a vampire after graduation, which is only a few weeks away. Bella feels bad that she's spending all her time with Edward and so she sneaks off to visit Jacob occasionally. Jacob invites Bella to come with him to a Quileute council meeting, and she accepts. Jacob and Bella spend the night together and listen to tribe legends, believed to be real by the Quileute. On one of the later visits, Jacob tells Bella he loves her, and kisses her, thinking that Bella loves him back. Bella, outraged that he would kiss her after he knows that she loves Edward, punches him in the jaw and breaks her hand. Jacob brings Bella home and is told by Edward that if he ever kisses Bella again, he would break Jacob's jaw. But Edward also claims that he would allow it to happen if Bella wanted to kiss him.
A while later there is a graduation party held at the Cullens' house that Jacob decides to go to, giving Bella a charm bracelet with a carving of a werewolf on it as a graduation present. While he's there he learns that Victoria has amassed a newborn vampire army to attack Bella. Jacob eagerly agrees on learning how to fight these vampires and to fight along with the Cullens to protect Bella. Their original plan was to have the werewolf, Seth, watch over Bella in a remote mountain place while the Cullens and the werewolf pack fought off the vampires. Bella, however, wanted Edward with her when she stayed in the mountains, and asked Edward. Edward agreed as long as Jacob would carry her to the place in the mountains so that her scent would be lost. They followed through with the plan, and Jacob carried Bella to the mountain hideaway.
While waiting for the battle to be over, Edward, Bella, and Jacob set up camp. A blizzard blows through the camp, and Bella to begins to freeze. Jacob comes in the tent and stays in Bella's sleeping bag to warm her up with his abnormal body heat, much to Edward and Bella's horror. Later on, Bella wakes up and Jacob leaves the tent. Bella and Edward then start discussing how they're marriage plans, and Jacob overhears their conversation, and runs away because of he's so upset that they're getting married. Upon Bella's request, Edward brings Jacob back and leaves them alone to talk. After some talk, Jacob says that he's going to go and kill himself because Bella doesn't love him. Bella then begs and pleads with him not to. Bella says that she'll kiss him if he won't commit suicide. Jacob agrees and they kiss (although he wasn't going to really go through with killing himself - it was a trick he used on her). Bella then realizes that she loves Jacob, but her love for Edward overpowers everything else. Jacob then leaves to finish the battle, and gets injured in the battle trying to save a fellow werewolf named Leah(who was trying to show off). Carlisle patches him up and worried Bella visits him. They talk and agree that Jacob should let Bella stay with Edward and to stop coming between them. Jacob reminds Bella that he will always be there for her whenever she needs him.
The epilogue is written from Jacob's point of view for the first time in the series. Jacob is sitting on the end of the cliff and Leah is trying to talk to him. Jacob scares Leah off and then returns home. At home he finds that Edward has sent Jacob a wedding invitation to Bella and Edward's wedding. With it a note was enclosed from Edward saying that Jacob did not have to come to the wedding, and Edward thanks Jacob for "everything". At the end, Jacob runs away in wolf form, leaving "Jacob Black" behind him, trying to escape the pain he feels from Bella's decision by trying to become a vampire.
In Breaking Dawn Jacob is first seen at Bella's wedding. Then after Bella returns from her and Edward's honeymoon he went to the Cullen's house to check if she was still human, but finds out that she is pregnant and sees that Bella has purple and blue bruses on her stomach from were the baby has kicked . As he returns to Sam and the pack they plan on killing Bella and the baby. He believes that it is wrong to go and attack them because the Cullens are innocent, and they should give the baby a chance. He starts his own pack of which he is Alpha, which Leah (who later becomes Beta) and Seth Clearwater join.
It is revealed that Jacob has imprinted upon Edward and Bella's daughter Renesmee, whom he calls "Nessie" because her real name is too much of a mouthful. (Bella is extremely irritated with the nickname and the fact that it catches on, herself and Edward even calling her "Nessie" at one point.)
He is extremely close to her, goes hunting with her, and for Christmas braids her a bracelet that is the Quileute version of a promise ring, much to the annoyance of Edward. Jacob has a strong desire to protect her, that she's safe, and wants her to have fun (which is why he hunts with her, since she prefers donated human blood to animal blood and human food; so he makes it a contest between the them.). It is hard for him to be separated from her, so he visits every day and almost never leaves the Cullen house. He states, though, that once Renesmee's growing slows down, he will go back to school.
Sam's pack stops trying to attack the Cullens, since there is a law that states that one cannot kill the object of another wolf's imprinting, due to the damage it would cause to the wolf in question.
Bella was planning to have Jacob run away with Renesmee to Rio de Janeiro, Brazil, and possibly from there to Isle Esme, if the Volturi had decided to attack. She had forged passports made for the two of them, with Jacob as Jacob Wolfe, and Renesmee as Vanessa Wolfe (since Bella assumed that that was a name that "Nessie" could be short for). She picked Jacob and not herself or any of the Cullens because both can go out into sunlight, it would be painful if Jacob and Renesmee were separated, and Jacob would be able to keep her safe much more effectively than anyone else, since he has a strong desire to protect her because of the imprint. Jacob and Renesmee did not have to run away, so Bella keeps the passports for the future.