A secret alliance, a broken marriage, a deadly agenda, and the daughter she never knew -- vampire mama Isobel was at the epicenter of practically ALL of the drama this week, which saw quite possibly the most amazing guest performance in the entire series thus far, courtesy of Mia Kirshner. The woman should win an award for general bad-assery from this episode alone. Because as much as she convinces you to love to hate her for much of "Isobel," Kirshner pulls out some revelatory material in the ep's final moments that instantly makes her one of this show's most intriguing and compelling characters. (Now, if the writers could just give some of that mojo to poor, suffering Caroline...)
 
With only one more episode to go before the May 13 season finale -- and the months of agonizing withdrawal that will surely follow -- Episode 21 also brought the focus back to the drama in almost every relationship in Mystic Falls: beefing besties Tyler and Matt, awkward ex-BFFs Bonnie and Elena, even the budding bromance between Damon and Alaric. And finally, FINALLY, someone in the show acknowledged that of which Elena is in complete and total denial: the growing love triangle between her, Stefan, and Damon! But first, Elena must discover the true nature of her undead birth mother. Alaric must also get his chance to confront Isobel for leaving him high and dry (and then turning into a vampire). And you thought running into your ex was bad. 
 
Keep some tissue on hand just in case. I'm just saying.  
 
[Full recap of Thursday's (May 6) "The Vampire Diaries" after the break...]
 
We pick up where last week's episode left off. Isobel has shown up unannounced at the Mystic Grill, where she greets Alaric. They small talk the way estranged spouses do: "How's it going?" "You're a history teacher now?" "Why'd you turn into a vampire and abandon me?" Isobel explains that the vampire life was what she wanted -- but then she also wanted Alaric to mourn her and move on with his life, so I guess nobody really got everything they wanted after all. 
 
Isobel coolly confirms that she's Elena's mom and that she knows Elena's been looking for her. She asks Alaric to arrange a meeting. Alaric, however, is hurt by Isobel's heartlessness -- that and the years of bitter, heartbreak she left him with -- and refuses. Isobel vampire-chokes her long-lost husband and threatens to kill off his students if he doesn't do as she wishes. Ah, marriage. An endless negotiation!
 
Elena calls her new bestie Damon to check in on Stefan, who's back to his good old normal boring self. He asks her to check up on Uncle John. 
 
Over at Mystic High, Vampire Weekend is playing in the background -- although really, isn't EVERY weekend in Mystic Falls a vampire weekend? Alaric has roped Tyler and Matt into helping build a Founder's Day float. Uh-oh, someone's noticed Tyler's broody-sensitive art skillz! The former BFFs are still not talking since Tyler totally hooked up with Matt's MILF of a mother. Meanwhile, Caroline Bings "Mystic Falls Founders Day" to show Bonnie how fugly last year's float was. Bonnie agrees. I'm about to Bing "Mystic Falls Founders Day" just to see if the same lame-O float pops up. Guess what? IT DOESN'T. Viral marketing FAIL. Caroline finally asks the uber-mopey Bonnie why she's been mad at Elena for weeks, but Bonnie's not telling. 
 
Damon meets Stefan and Elena in Alaric's classroom, where they've just been informed about Isobel's demand. Speaking of Isobel… Uncle John rolls up to a newly foreclosed house where Isobel's entertaining herself with two slutty humans. She's used her vampire mojo to reeducate a gay cowboy into being straight, which totally doesn't sit well with Uncle John. After weeks of playing meek and domestic in Alaric's flashbacks, Mia Kirshner FINALLY displays her deliciously dangerous and acerbic powers here in full Elvira mode, sassing Uncle John around. They've been partners the whole time, in cahoots to retrieve the mysterious Johnathan Gilbert gadget! Isobel gives Uncle John a good old-fashioned bitch slap and takes over their operation.
 
Meanwhile, back at the high school Damon wonders precisely if Isobel and Uncle John are in cahoots and after the Gilbert gadget, but all Alaric knows is that she wants to see Elena. But duh, Elena wants to meet her! Otherwise all of her brow-furrowing biological mommy issues have been for naught!
 
Elena meets Isobel at the Grill, with Stefan sitting a few tables away for protection. Even Isobel is weirded out by Elena's resemblance to Katherine. She explains that Katherine came to meet her after she turned, and that she helped her get the magic necklace she wears that allows her to walk around in the sunlight. (Will we ever meet the magical vampire jeweler who sold all this bling to the vampires of Mystic Falls??) Elena wants to know who her father is, but Isobel only says he was "a teenage waste of space." Elena's turned off by her dear mother's complete and total disregard for human life. Isobel also has no regard for manners, and asks Elena why she doesn't get it on with both Salvatore bros like Katherine did before her.
 
Alaric and Damon wait outside and work on their bromance. Damon wonders why Alaric still seems to care about Isobel. Alaric sees that the Isobel he loved is nowhere inside of Vampire Isobel, but he wonders if there's truly no shred of humanity left in her when there's tons left in Stefan, and a itty bitty sliver left in Damon. Damon explains: vampires can opt to turn off their humanity and be 100% cold-blooded. Stefan, however, "wants to feel every episode of 'How I Met Your Mother'" and keeps his humanity set to 11. Damon denies that he's let himself feel guilt or remorse, but Alaric sees that he hasn't lost his feelings. These guys are such besties in the making.
 
Back inside, Isobel tells Elena why she's really there: she wants the Gilbert gadget. She also spills that she had a crush on Uncle John when she was younger, and that he was the one who first turned her on to vampires. Elena wonders why Isobel even wanted to turn, and Isobel promises her that when she gets old, she'll join the Bella Swan anti-aging club and want to join her vampire boyfriend in eternity. When Elena refuses to help her, we learn that Isobel has a few motherly qualities after all -- she's got eyes in the back of her head that spot Stefan approaching, and she also guilt trips her daughter into getting her the gadget, or else. What a very special Mother's Day episode this is! Call your mother and tell her you thought of her tonight.
 
At the Gilbert house, Aunt Jenna eavesdrops as Jeremy calls his vampire girlfriend Anna, who hasn't checked in since she came home to find her mother's dead-undead body in the doorway. Uncle John bursts in and awkwardly asks Jeremy when he saw Anna last, since she wasn't home when he totally killed Pearl and Harper. John creepily tells Jeremy he's there to talk about girls if he needs to. Jeremy is as weirded by Uncle John's sudden paternal streak as we are. Uncle John was so much more interesting when he was on "Alias."
 
Isobel comes home to find Damon shirtless in her living room, playing strip poker (and losing, thank you writers) with Isobel's hypnotized she-slave. Isobel asks him if he brought the Gilbert gadget and pulls his hair, which Damon seems to like. Kinky. He wants to know why she's looking for the gadget, and she tells him they're both on the same side: Katherine's. Isobel tells Damon that Katherine wants him to give Uncle John the gadget, which is just the sort of brilliant psychology that she'd be using if she were lying, too. They circle and swipe at each other, which is apparently the evil vampire version of foreplay. Just as it looks like Damon's about to shtup his BFF's wife, he pins Isobel to the ground and tells her to back off of the people he cares about -- namely, Elena -- and that if Katherine really wants something from him, she'll have to come ask for it herself.
 
Bonnie shows up at Elena's house feeling bad for being a bad BFF. She apologizes for her recent behavior and promises to be there for Elena. They hug as Elena tells her about meeting Isobel. Meanwhile at the high school, Tyler's also trying to make up with his former bestie. Matt rebuffs Tyler's attempts at apologizing. (Everywhere we look there are Mystic High Timberwolves signs -- when will "The Vampire Diaries" get its werewolves, already??)
 
Elsewhere, Bonnie's asked Elena to meet her in secret so she can show her something in Emily's spellbook. Which must remain safe and secret EVEN THOUGH SHE'S BROUGHT IT TO SCHOOL. Emily Bennett was the one responsible for all of Johnathan Gilbert's magical inventions; she witchified them, rendering his useless gadgets powerful. Emily's book -- really, a diary of illustrated spells -- reveals that she created the magical Gilbert vampire compass, the Salvatore rings, and the mysterious gadget that Isobel and Uncle John are after. Bonnie reads the witchy code language and learns that the gadget actually has two parts, only one of which Damon possesses, and that it's… a weapon! An anti-vampire weapon!
 
Jeremy finds Elena outside Mystic High. Elena only now finds out that he and Anna were dating. Adopted sister FAIL! Jeremy's concerned about Anna's safety, and when Elena says she doesn't know anything about anything, Jeremy calls her out on her season full of lies. He storms off before Elena can tell him anything useful, but before Elena can storm off in turn, Isobel surprises her. Isobel says she now wants to be involved in Elena's life, but when Elena refuses Isobel shows her that she's done her homework and can point out every one of Elena's vulnerable human friends -- witchy Bonnie, yappy Caroline, and ex-boyfriend Matt -- within reach. To demonstrate her willingness to hurt Elena's loved ones, Isobel has her cowboy slave jump on the float Matt's working on, pinning Matt's arm underneath. As Tyler and Stefan rescue Matt from under the float, Isobel has her slutty girl slave kidnap Jeremy, and promises to kill him if Elena doesn't get her the Gilbert gadget. 
 
Back at her foreclosed mansion, Isobel summons Uncle John to show him her new captive: Jeremy. He pleads with Isobel to let Jeremy go, appealing to the old Isobel somewhere deep down inside. But Isobel orders her slutty slaves to attack and subdue John, then removes his life-protecting ring and leaves him bleeding on the carpet.
 
Meanwhile, Bonnie's joined Elena and Stefan's brainstorming session to figure out how to get the gadget from Damon. They appeal to Damon; if Bonnie can remove the gadget's spell before they give it over to Isobel, she and Uncle John can't use it to kill him or any other vampires. Damon prefers to storm Isobel's mansion, and wonders if Bonnie's even up for the caper. He OBVIOUSLY hasn't noticed that Bonnie's been foregoing her usual hair and make-up regime in order to practice her magick. She proves her witchy powers… by hurling Damon's favorite book out of the shelf with her mind! Just the trick that'll get them past Isobel and her deadly hypno-sluts. Damon gives in, because he's a wuss when it comes to Elena's big brown puppy dog eyes, and hands over the gadget while Stefan notices every single moment that Damon's hand lingers in Elena's. Beef up that love triangle!
 
Over at Isobel's, Jeremy asks his beat-up uncle what Isobel's after. He explains his secret agenda: there's a group of old-timey vampires out for revenge on the people of Mystic Falls, and he and Isobel both want to kill them for different reasons. Jeremy insists that some vampires are good, but Uncle John is a staunch conservative. Uncle John tells Jeremy it's in his blood to hate vampires and that his late father, John's brother, was the one keeping the Gilbert family vampire hunting legacy alive. 
 
Damon, Elena, and Stefan watch as Bonnie levitates the Gilbert gadget and makes all the candles flicker, removing the weapon's powers. Elena goes to meet Isobel in the town square, where both of them have brought back-up. Isobel tells Elena to call Jeremy, who is home safe with Uncle John. A relieved Elena questions whether Isobel was ever going to hurt Jeremy, but Isobel dispels her hope: "Don’t look for any redeeming qualities in me. I don't have any." Isobel says she knew Damon would give Elena the gadget because he's in love with her, which prompts Damon to awkwardly glance sideways at his brother. Stefan, however, appears somewhat unsurprised. They're gonna have an interesting conversation when they get home...
 
Elena hands over the gadget and sarcastically thanks Isobel for disappointing her so much that her adoptive dead mother is once again her favorite dead mother. Isobel says goodbye, warning Elena that as long as she has the Salvatores in her life, she's doomed. Isobel and her entourage leave, and Elena falls into Stefan's arms. They both give sidelong looks at Damon, who excuses himself as Isobel's truth-speaking sinks into them all.
 
Back at home, Elena tries to make up with Jeremy, who's still worried about Anna. He stops her short to reveal that he already knows everything about vampires after reading her journal -- fair enough, considering that she had Damon erase his memory. He shuts her out as she tries to apologize. 
Isobel shows up at the high school after hours to say goodbye to Alaric, looking emotional for once, as if she's temporarily turned her humanity back on just to have a moment with him. He wonders why she came if she doesn't care about him; she wonders what he thought he'd find after years of searching for her. He removes his vervain charm and takes off the magical life-protecting ring she gave him years ago, throwing it back to her, and dares her to either kill him or compel him if there's truly no smidge of Human Isobel left. 
 
She pins Alaric against the wall with her vampire strength, then tells him that turning into a vampire was her choice -- a choice she'll regret for eternity. Looking deep into his eyes, Isobel tells Alaric that she loved him and that it hurts her to remember what she gave up, and -- hold on, pass the Kleenex -- and then, she compels him to forget about her so he can move on with his life. Sniff. And just like that, she's gone. 
 
But wait, there's more! Jeremy turns out the lights and shuffles off to bed in his jammies, but is happily startled by Anna! Until she tearfully tells him her mom's been killed. She's come to Jeremy's because she has nowhere else to go. 
 
Over at the Salvatore mansion, Stefan brings up the issue of What Isobel Said. Stefan knows that Damon and Elena are friends -- she's his only friend, Damon admits -- and wants to make damn sure that history and their 19th century ménage a trios won't be repeating itself. Damon deflects and changes the subject by wondering when, now that she's met her evil birth mother, Elena should be enlightened about the man who's probably her birth father: Uncle John! Oh, and he's always going to be there for Elena, so Stefan will have to just deal with it. 
 
On her way out of town, Isobel calls Uncle John to tell him that she's left the gadget on his doorstep. In exchange, he promises to do as Katherine wishes and kill all of the evil tomb vampires. And for extra measure, Mama Isobel also wants him to off Stefan and Damon -- because she doesn't want Elena to suffer in eternal vampire hell, too. Uncle John promises to protect Elena from her vampire boyfriends… because he IS her daddy!
 
Oh snap -- THERE'S EVEN MORE! Without giving away the truth about witches and vampires, a jittery Bonnie admits to Caroline that she lied to Elena. She didn't remove the Gilbert gadget weapon spell after all! And Uncle John's going to use it to kill Damon and Stefan!
 
Next week: It's Founder's Day! Bonnie's out of control, and Stefan's in trouble!