The Broken Angels

Theresa maria swan is a young agent who does not know who her parent were. She is the world most best agent and also an avenger. She work for S.H.I.E.L.D.She knows she is different from other. She has power.......
She is sent to investigate vampire in forks. There she met Edward Cullen but he left her.
She has moved on but she is sent back to fork because there is high tense weather above fork which indicates the arrival of aliens. When she return she finds The Cullen are back.
Then suddenly she feel her skin burning and when she look their is a dark mark.
Who is she?