Finally! Our favorite quasi-evil vampire is back on "The Vampire Diaries!"

Katherine rings up Damon to tip him off of Stefan and Klaus’s location. The duo is in Chicago, the place of Stefan’s old ripper days. It’s a blast from the past as we get glimpses of Stefan’s past, although he doesn’t seem to be able to remember much of it.

Back in Mystic Falls, Elena gets an early morning wake-up call from Damon broad chest. This weekend, they’re traveling to Chicago to try and get Stefan…again. On the way, Elena learns a little bit more about Stefan’s blood thirsty past through his diary entries to prepare her for what’s to come. Damon takes her to Stefan’s old apartment and shows her a secret room with a wall covered in his victim’s names. He leaves Elena there to come up with a plan as he scouts out the two.

Stefan and Klaus go to a bar called Gloria’s, the same place where the flashbacks take place. Klaus goes there looking for, you guessed it, Gloria, a powerful witch, to find out why he can’t create more hybrids. She tells him that in order to fix the problem, they would need to contact the original witch who cast the spell. Klaus is pretty down in the dumps as that witch is dead, but as luck would have it, Gloria can contact her on one condition: that Klaus brings her Rebecca. Before we can even ask who Rebecca is, Stefan stumbles upon a disturbing photograph of him and Klaus together from the 20s. What?!

Meanwhile, Caroline’s dad is torturing, I mean, conditioning, her in an old family vampire dungeon. He’s exposing her to sunlight so she’ll associate that pain with her appetite and urge for blood. She tells him that they both know they can’t change her, but he doesn’t listen and opens t he window again. Talk about tough love.

So Stefan’s trying to get some answers about their history together out of Klaus. Apparently, Klaus hated Stefan at first. Turns out, Stefan was romantically involved with Rebecca, who’s Klaus’s little sister. They approach a series of coffins in a dusty warehouse, presumably all housing Klaus’s currently dead siblings, until they reach Rebecca’s. As Klaus yanks the knife out of her to bring her back to life, we learn that Stefan was the one that taught Klaus a couple of gruesome ripper tricks. Stefan doesn’t believe Klaus when he says they were even friends, so to prove it to him, Klaus brings Stefan to his old apartment, where Elena just so happens to be hiding. She slips into the hidden room, but unfortunately it’s the one that Klaus uses to prove to Stefan that he once trusted him with this secret. Stefan walks in and he’s suddenly face to face with Elena for the first time. After some really intense eye contact, Stefan says to Klaus, “Look what I found.” Thankfully he meant a bottle of alcohol and not Elena. Phew! That was close.

Stefan and Klaus return to Gloria’s. While they wait for Rebecca to show up, Klaus gives Stefan more pieces of their puzzling past. Not only did Klaus want Stefan to be his wing man because he liked his torture methods, but once upon a time, Stefan also wanted to be his wingman. Stefan still can’t really come to terms with this because he doesn’t recall any of this. We go back in time once again to a very much in love Stefan and Rebecca at the same bar, when all of a sudden bullets are flying and the place is being raided. When they realize wooden bullets are being used, Klaus and Rebecca must flee. Klaus compels Stefan to forget about everything and he almost seems sincerely regretful. It seems that the originals are running from something themselves.

Stefan manages to slip out of the bar when Damon catches his eye. Naturally, he’s furious that Damon is still trying to bring him back, telling him that Elena is once again in danger because Klaus’s witch is on the verge of finding out the true reason why he can’t make hybrid buddies. Of course, Elena’s standing right there so Damon tells him to tell her himself while he goes in to distract Klaus. All Elena wants is for him to come home. She tries to sedate him with vervane during their embrace, but he’s too quick for her. Stefan gives her the ultimate reality check as he tells her that it’s over and that he never wants to see her again.

Caroline’s not doing too well herself, seeing as her dad is still trying to ‘fix’ her so he doesn’t have to kill her. Sheriff Forbes comes to her daughter’s rescue, toting a gun in one hand and Tyler Lockwood in the other. When they get back home, there’s a peaceful resolution between mom and daughter, and Tyler lends Caroline a shoulder to cry on.

Klaus ventures back into the warehouse looking for Rebecca. He’s taken by surprise as she drives the knife into Klaus, payback for when he killed her for choosing Stefan over him. She’s still royally pissed that he killed her, so Klaus brings in Stefan as a peace offering. He then compels Stefan to remember everything, including Rebecca and Klaus. Turns out, Klaus wasn’t lying, and they’re really all one big happy family. But that joyful reunion is short-lived as they realize that Rebecca no longer has what Gloria needs, which turns out to be a necklace that Gloria gave her, the same necklace that Elena is conveniently wearing. Oh, nuts!

So the plot thickens! There’s a darker dimension to Stefan that we haven’t met until now. Is it really over with Elena? Are he and Rebecca going to pick up where they left off? And what about Jeremy’s “I see dead people” problem? One thing’s for sure: Katherine’s back and we know she’s gonna stick around as long as there’s trouble.