Personal history: Jasper served as a Major in the Confederate army during the Civil War.  The vampire family that changed him in 1863 (TL) was very different from the Cullens in their dietary habits –they fed off humans. (PC2) Jasper became depressed over his way of life and sought something better.  His search led him to Alice in 1948 (TL), which in turn led him to Carlisle in 1950. (TW14) (TL)

Jasper has the most difficult time with the lifestyle set by the Cullen family.  He avoids contact with humans, as he is more tempted than the others to drink from them.  Going to school is a difficult task, but he does it for Alice. (PC2)

He would do anything for Alice, as she is his whole life.  Even though he treats the other members of his family with respect, he isn’t bound to them the way he is to Alice. (PC2)

Jasper uses the last name of Hale because he and Rosalie look so much alike and people assume them to be twins.   The vampires tend to go with whatever the humans are willing to believe.  Rosalie insists on using Hale as a last name, and therefore, Jasper took it as his, too.