Joseph Morgan and Daniel Gillies Joseph Morgan and Daniel Gillies

Spoiler alert: The following reveals something major from Thursday's episode. Read at your own risk!

The Originals are back from the "dead" on The Vampire Diaries, and they have a bone to pick with Klaus.

On Thursday's episode "Bringing Out the Dead," Klaus' sister Rebekah (Claire Holt) was undaggered by her brother Elijah (Daniel Gillies). But it's not exactly a happy reunion for the siblings as Rebekah recently learned that Klaus (Joseph Morgan) was the one who killed their mother 1,000 years ago.

"He's absolutely going to feel some aggression aimed toward him," Holt told on our recent visit to the Atlanta set. She's so unhappy about the fact that he lied to her all this time and she feels betrayed by him."

The Vampire Diaries Bite: Joseph Morgan tells us what will devastate Klaus

Of course, Rebekah isn't the only one who should be angry. Esther (Alice Evans) shocked Klaus when she was freed from that mysterious fourth coffin.  "[Rebekah] is really excited to have her mother back and [now they'll be] a powerful unit," Holt adds.

Watch the video for more on what Rebekah's return means for Elena and how the family will wreak havoc during next week's big formal ball.