Showing Dark Reunion by L. J. Smith

Elena: transformed, the golden girl has become what she once feared and desired. Stefan: tormented by losing Elena, he's determined to end his feud with Damon once and for all - whatever the cost. But slowly he begins to realize that his brother is not his only enemy. Damon: at last, he possesses Elena. But will his thirst for revenge against Stefan poison his triumph? Or can they come together to face one final battle?