Bree Tanner was a vampire created by Victoria, with the purpose of fighting to kill the Cullen family with her army of newborn vampires. Despite her ignorance of the vampire laws, her act of surrendering, and showing adequate control of herself, she was cruelly executed by members of the Volturi by Jane’s order.
You can head over to the Twilight Wiki for the run down on Ferland’s character or scroll down to view the new video which I’ve embedded below.