Klaus had possessed Alarik's body,Klaus has always been a very bad man, he only does things that will be worth something to him, he does things for himself and only for him , and so today was the day of the transition so he could return to his body, the moon was full, when Klaus' body came out of the coffin the first thing he saw was you, the duplicate of Katherine Pierci and then he said "So this is Katherine Pierci's duplicate?" he asked with a curious yet fascinated tone.