Elena finally flexed her vampy muscle in last week's episode of The Vampire Diaries when she killed Conner. However, in this Thursday's installment, "We All Go A Little Mad Sometimes", Elena's actions won't be what you're talking about on Friday.
I don’t think Elena is the vamp whose actions you’ll be talking about after this week’s episode. And let me tell you, what he or she does is going to ROCK. THIS. FANDOM.