Some possible thoughts include: how did Elena get down here so quick, is Damon trying to strangle Elena, is Damon trying to 吻乐队(Kiss) Elena, 或者 maybe he realized it was in fact Katherine. Stefan seems to be the most welcoming towards Katherine.
Katherine’s mind games are getting on everyone’s nerves, but Damon, Stefan and Elena realize that her knowledge of Mystic Falls history will help them stay alive.