His real last name is Whitlock and was born in Texas in 1843. In 1863 at age 20, while returning from the battlefield, Jasper meets a vampire named Maria and two other vampire that accompany it. The boy is frightened by the three women but simultaneously feels attracted by their beauty and Mary turns it into one of them.Many decades after his transformation, he befriended another vampire named Peter who, despite his experience and his talent, he fought unwillingly. The two boys were given the task of getting rid of vampires that exceeded the status of the newborn. During this assignment, one evening Peter was furious with Jasper for his failure to pardon some infants and Jasper attacked him. Peter ran off with a baby named Charlotte and five-year, he returned to Jasper in the very moment when the vampire and was depressed about changing lives. Peter Jasper told her how to live with Charlotte and convinced him to escape from that situation without regrets. Jasper became convinced that there was an alternative to fighting and joined them, traveling with the couple for some time. In 1948, his life took a turn when he found himself in a bar in Philadelphia. That day he was approached by a young and handsome vampire named Alice. Alice through his powers had seen that Jasper needed her even before the Jasper knew it was one of the few vampires have special powers, in his case to be able to see in the near future. Jasper also has a power which is able to manipulate the emotions of the people who surround him. Thanks to Alice, Jasper found hope and then the two lived together by indissoluble spiritual link. In 1950 Jasper and Alice Cullen reach and have since become part of the family. Jasper decided to take the surname such as Rosalie Hale as being both fair and also very similar to human eyes, it was fitting suggests that they were twins. The Cullen family, though composed of vampires, has chosen not to feed on humans but animals defining their lifestyle "vegetarian". Jasper adapts to this kind of life but, having spent a militaristic and violent, is very hard to resist the blood and keeps aloof from the rest of his family when he has to interact with humans. When his brother Edward falls in love with the human Isabella Swan, Jasper tries to stay away or risk attack her. Its strength is tested in the evening when the girl is at home to celebrate their birthday. Bella, while opening a gift, he injured a finger on the paper package, triggering a violent reaction that Jasper can not resist the smell of blood. Edward, with the help of his brother Emmett and Carlisle, manages to avoid the worst. Because of this reaction, Edward leaves Bella convinced that the presence of her family, she will always be in danger. Jasper turns out to be very useful to the family when a group of newborn vampires led by Victoria, the Cullens decide to attack to avenge the death of James. Victoria is determined to avenge the death of mate, which occurred at the hands of Edward killing Bella. The experience of the fighting occurred in the Army of Mary, make Jasper the only one able to help his family to defend themselves from these vicious attacks, and organizes their training sessions to be attended also werewolves that although the enemies of vampires , ally themselves temporarily with the Cullens to save Bella together and defeat an enemy more dangerous.