In Twilight, Jasper accompanies Alice and Bella when they are hiding from James. He uses his ability to calm Bella when she is stressed or afraid. In New Moon, he attacks Bella after she gets a paper cut, prompting the Cullen family to leave Forks to protect Bella. In Eclipse, Jasper teaches the werewolves and vampires fighting techniques to defend themselves against newborn vampires. In Breaking Dawn, Jasper leaves with Alice to find a vampire-human hybrid, and returns with her to defend Renesmee from the Volturi.
Jasper Hale (born Jasper Whitlock)
Jasper Hale (born Jasper Whitlock) is the adopted son of Carlisle and Esme, adoptive brother of Edward, Emmett, and Rosalie, and husband of Alice. He was born in Texas and joined the Confederate States Army in 1861 to serve in the Civil War. Due to his extremely charismatic personality, he ascended through the ranks quickly. Jasper was turned into a vampire in 1863 by a vampire named Maria when he was 20 years old. As a vampire, he gained the ability to manipulate the emotions of those around him. Recognizing his high rank in the army, Maria decided to change him into a vampire to help her claim territory in Monterrey. Jasper's responsibility was to train young vampires and then kill them when they were no longer useful (about a year after their transformation- when their strength began to fade). After about a century of this, he grew weary of the lifestyle and joined an old friend, Peter, and his mate Charlotte. Jasper left the two eventually, not wanting to feed on humans because he could feel his prey's emotions as they died. Alice, foreseeing that they would be together, met him in a half-empty diner in Philadelphia, and together they sought out the Cullen family. Due to his past, where he was able to feed on humans whenever he chose, Jasper lacks strong self-control. He is described as tall with honey blond hair, and is muscular but lean. His body is covered with crescent-shaped scars, after the many years of fighting and training newborn vampires.