 It also turns out that Elena is the doppelganger of Katherine Pierce, a woman who, centuries ago, seduced the Salvatore brothers and turned them into vampires, turning their vampire hunting father against them, though Stefan ends up killing him.Katherine was presumably trapped in a tomb beneath the church and Damon is planning on releasing her.Lexi, a friend of Stefan's shows up and befriends Elena, but is killed by Damon, driving a wedge between brothers.