How Do 'TVD' Doppelgangers Work? The 'Vampire Diaries' & 'Originals' Crossover Is Here & This Stuff Is Confusing

Here comes that word again, Vampire Diaries fans. Remember when Julie Plec promised no more doppelgängers? I know you do, because the TVD fan base collectively cheered because the Petrova Doppelgänger storyline was one of the most long-winded aspects of The CW supernatural drama. Well, new series, new opportunity to resurrect an extremely old storyline. The Vampire Diaries and Originals crossover airs on Nov. 3 and, yes, there will be a doppelgänger. The episode, titled "Red Door," guest-stars Nina Dobrev as Petrova Doppelgänger Tatia — another copy that fans haven't met up until this point AND who will come between two brothers. God, Julie Plec, do doppelgängers have any other purpose than to create love triangles? You've got to have something else for us if we're going down this road again, right?

I know what you're thinking: "How many times am I going to have to hear that word this time?" Unfortunately, that's not a question I can answer. But I can offer you the comforting theory that Tatia's appearance might only come into play during Monday night's episode of The Originals when Esther forces Elijah to remember what was possibly the first time he ended a relationship for Klaus' benefit. However, regardless of how you feel about the Petrova Doppelgänger storyline returning on Monday night, you could probably use a refresher on what and who exactly the doppelgängers are and why it feels like you've spent the past five years of your life hearing about that (well, I mean, it has been five years).

The main thing you need to remember when it comes to the doppelgängers — also known as Shadow Selves — is that they've been born to die for centuries to maintain the natural order that was disrupted by Silas and Amara becoming True Immortals. In addition to that purpose, however, their blood also possesses magical qualities that makes it a powerful binding agent in complex spells. And now, let's talk the long list of existing TVD doppelgängers:

The First: Amara

Status: Dead

Amara was first introduced at the beginning of TVD Season 5 as Silas' former true love and the original Petrova doppelgänger. She's the reason why Tatia, Katherine, and Elena exist — thanks, Amara. After drinking the immortality elixir that was meant for Qetsiyah so that she could live forever with Silas after their wedding, Amara became the supernatural being that required Shadow Selves to please the natural order that her immortality disrupted.

Tatia

Status: Unknown

Tatia is the next known Petrova doppelgänger and it's thanks to her magical blood that the Original vampire family exists. Tatia is, obviously, a shadow of Amara and she's the character that will appear on The Originals "Red Door" for the first time. What's her deal? Well, both Elijah and Klaus fell for Tatia, even though she already had another child by another man. Allegedly, the pair feuded over her and so Esther took her and used her blood to turn them into Original vampires.

Katherine

Status: Dead

Oh, Katherine, how I almost miss you, you raging Traveler-turned-vampire psychopath. Katherine, like Tatia before her, also had ties to Klaus and Elijah. After the Mikaelson brothers were first introduced to TVD, we learned that Klaus had once planned to sacrifice Katherine to break the Sun and Moon curse. Of course, Katherine escaped by becoming a vampire and spent many of her immortal years running from Klaus' wrath. As soon as she became a vampire, however, her doppelgänger blood became useless, as the power it contained can only be harnessed while the doppelgänger is human.

The Last: Elena

Status: Alive

Elena was the reason Klaus turned up in Mystic Falls in the first place because he'd learned the the doppelgänger blood not only could break the (fake) Sun and Moon curse, but it could also turn werewolves into hybrids. Elena is the last known Petrova Doppelgänger, but now that she's also become a vampire, her blood is also useless.

Image: Annette Brown (2), Quantrell Colbert, Bob Mahoney/The CW; The CW (screengrab)