Secret hookups, old grudges and a dark past never revealed until now – “The Vampire Diaries” had fans on the edge of their seats throughout episode 9, “The Cell.” So, what happened? We’re breaking down the top moments of the night.

Damon’s Augustine Flashback

In 1953 Damon returned to the old Salvatore boarding house in Mystic Falls at the request of his relative, Joseph. But what Damon didn’t realize is that Joseph sold him out to Dr. Whitmore.

Locked in a cell at Whitmore, Damon was tortured for five years– cut open and had pieces of his eyeball removed – all in the name of science. Fed one small cup of blood a day, Damon only had one thing to keep him going – his cell neighbor, Enzo.

Enzo was locked up at Whitmore 10 years before Damon arrived. A soldier in World War II, Dr. Whitmore discovered the vampire while he was working in the fields, and had him drugged and shipped back to the U.S.

The pair developed a friendship, and eventually Enzo came up with a plan for them to escape on the one day a year that Dr. Whitmore let them out of the basement – New Years Eve. Every year the doctor held a party where he showed off his vampires and used their blood to wow his gifts. On the one cup of blood, neither vampire would be strong enough to escape. However if one vampire drank both cups he would be able to fight back. Damon drank the extra blood for a year and in 1958 they put their plan into action.

With his extra strength, Damon attacked Dr. Whitmore and his guests. However in the process of slaughtering them he ended up starting a fire and was unable to help Enzo escape. Torn about leaving his friend behind, Damon shut off his humanity and fled … abandoning Enzo in the burning house.

Elena & Aaron’s Discovery

Realizing that something went wrong with Damon and Dr. Wes, Elena enlists the help of Aaron. While she doesn’t tell him the truth (like the fact that she’s a vampire and Aaron’s legal guardian is a psycho), she starts getting her classmate to think about the recent campus deaths … and how they don’t add up to suicides.

Elena’s chat with Aaron is cut short though when they enter the Whitmore house and she learns that her friend is actually a descendant of the Whitmore’s. And that’s not all she discovers– when Wes shows up he reveals that Elena’s dad was one of the best doctors that Augustine ever had.

Drugging Elena, Wes throws her in a cell next to Damon while he explains Aaron’s family history to him. Handing him a watch that belonged to his great grandfather, Wes reveals that Aaron’s parents weren’t really killed by animals. They were really killed by vampires, and Wes was the one that found their bodies at the campsite.

“That’s why I continued your fathers work,” Wes tells Aaron. “So this could never happen again.” But that’s not a suitable answer for Aaron, and he punches his guardian before walking out and heading to see Elena.

Damon’s Revenge

Upset over learning about vampires and that his parents were killed by one, he asks Elena if she’s the one that murdered not only them, but Megan and Jesse. Elena tells him that she’s innocent, but Damon drops a bomb – he’s the one responsible for killing Aaron’s parents.

Damon explains that after being tortured by Dr. Whitmore for five years he plotted his revenge. Since killing the doctor wasn’t enough, his plan for revenge was to kill the Whitmore descendants but leave one alive. That person would grow up and start a family and Damon would start the process all over again of killing that next generation.

Elena’s disgusted by Damon’s revenge reveal and demands to know when the last time he killed a Whitmore descendent was. Unfortunately for her, the answer is worse than she imagined – the last Whitmore he killed was this past summer while they were together… and it was Aaron’s guardian and aunt, Sara.

Needless to say, Aaron is not pleased about the latest discovery and shoots Damon in the head.

Mystic Falls Drama

Back in Mystic Falls, Caroline is working on helping Stefan with his PTSD. Using the safe that he was locked in for three months, Caroline’s plan is to lock him back in there to get him to overcome the ordeal. But when Caroline’s plan fails, Katherine comes up with her own … get in the box with Stefan!

The theory is that Stefan will help everyone but himself. Since being locked up triggers his “ripper” side, Katherine’s life is in danger in the box – so it’s up to him to gain control or kill her. And while Katherine should be treading carefully in that box, she uses her time with Stefan to accuse him of using the physical pain of the safe to cover up his emotional pain of losing Elena.

Katherine’s psychological breakdown in the safe help Stefan overcome his PTSD and also does something else … brings the pair closer. In a jaw dropping moment at the end of “The Cell,” Stefan grabs Katherine and passionately engages her in a steamy lip lock.

Episode 9 of “The Vampire Diaries” concluded with Damon waking up to find Elena gone. But Aaron didn’t help Elena escape. Instead Dr. Wes has her strapped up to a table next to another vampire … number 12144 … Enzo.

What did you think of “The Cell”? Let us know your thoughts on “The Vampire Diaries” in the comments section.