Credit: Bob Mahoney/The CW ©2011 The CW Network, LLC Photo: Matt Scowls in Season 2, Episode 16: "The House Guest"

We love those moments on The Vampire Diaries that make us gasp, pause, and rewind — and Episode 16, “The House Guest,” was chock full of them. Here are the five scenes that left us with our jaws agape this week.

5. Guess who’s coming to dinner
New rule for the Gilbert house: Whenever someone shows up unannounced, don’t open the door. Seriously. If Elena and Co. had followed that dictum already, Elena’s birth mother Isobel wouldn’t be able to waltz back into their lives as she did at the end of “The House Guest.” In what might be he evilest timing ever, the occult-historian-turned-vamp-tramp showed up minutes after Alaric assured Jenna that his wife was dead. “You must be Jenna. I’m Elena’s mother,” she said. Our response: What the?! [Insert door slam!]

4. Killer Kat
How many more times can Lady Pierce stab Damon in the heart? Apparently, a lot. Before Katherine sent Daddy Warlock to the witch place in the sky, she killed any new hope the sexiest Salvatore might have of her truly caring for him. During one of their moments alone she confessed that John Gilbert told her how to get out of the tomb. But the info came with strings attached. “He gave me a choice: Either I stay and help with Klaus or he kills Stefan,” she said. Damon pointed out, “But he still tried to have me killed.” Kat’s reply? “Right. As part of the deal I could only save one of you.” And, with that, once again she flat-out chose Stef over Damon — to his face. Major ouch!

3. Luka flames out
Poor invisible Luka. He was only doing his father’s bidding when he magic’d into the Salvatores’ house, looking for Elijah’s body. Their plan to pull out the dagger and let Eli do his heart-snatching thing was stellar. But Katherine’s vamp senses were sharper. And Damon was trigger happy with a flamethrower. When the elder Salvatore came to Kat’s aid, he lit up the room. And even though Luka was physically miles away, the teen warlock burst into flames. R.I.P. Baby Warlock.

2. Daddy Warlock goes off
After watching his only son burn to death right in their living room, Doc Martin went postal with a capital ‘P’. Looking to kill Elena, the warlock bum-rushed The Grill. He kiboshed the band and offed the lights. Then he started setting everything on fire. His rage was unchecked. When Bonnie tried to stop him he shut her down. Next he gave Caroline a vamp aneurysm. When Matt ran to help her, broke a bottle and jammed it into the dude’s neck. It was like prom night in Carrie. Only we weren’t rooting for the scene wrecker.

1. Matt Learns the Truth
“What the hell?” Matt cried when he woke up in Caroline’s room. Memory of what happened at the Grill was fresh in his mind: They’d made up. They canoodled in the men’s restroom. Then... His neck. Caroline’s face. The blood. “I drank your blood,” he said. “You were dying,” Car replied. “My blood healed you.” What followed was the most awkward conversation that could have ended his rollercoaster of a night. After Blondie copped to her bloodsucking nature, Matt lost it. But not for the reasons you’d expect. He remembered what his sister Vicki had said in the hospital last year after she was mysteriously attacked. Then he remembered Caroline was the one who found her body months later. “What did you do to my sister?” He yelled. “What did you do?!”