The Vampire Diaries executive producer recently revealed that the series almost turned into a huge franchise that would have opened new doors to its fantasy universe. Still, the show became a cultural phenomenon when it was released, and it continues to hold on to audiences long after its spin-off, Legacies, was canceled - though some fans contemplate the plethora of retcons.
Like most long-running shows, it had a winding and complex story, which often suffered from a lot of retroactive continuity, where the lore got significant changes as it progressed. Everything, from love stories to sire bonds and origin stories, was backtracked in later seasons after rules were already in place regarding them. The Vampire Diaries would have looked a lot different if these retcons didn't exist.
The Moment Elena Fell For Damon
Many fans were confused and outraged that "the" moment that Elena was supposed to have realized her feelings for Damon was when he returned Stefan's necklace to her at her birthday party. This was mainly because Elena was so invested in finding the humanity-less Stefan at that point in season 3, that the retcon made little sense.
Damon and Elena had countless amazing moments which could have been chosen for this pivotal shift. It made no sense since Elena and Stefan's bond was so strong at that point that she recognized him on a silent phone call, too.
The Sire Bond
The sire bond was a complex relationship that was initially shared by just Klaus and his hybrids, the reason for which was their gratitude to him for halting their constant cycle of turning into wolves every full moon. So, when Elena got sire bonded to Damon, it was completely unexpected.
She had no reason to be grateful to him for anything, and it felt like a forced way to add another complication to Damon and Elena's relationship. She had chosen Stefan already, so the sudden attachment to Damon was a complete retcon.
The Way The Cure Worked
The cure to humanity was a contentious tool in the The Vampire Diaries universe, but it became a lot more ridiculous as the laws about it kept changing. At first, it was a single dose which could only be used by one person — this ignited a war between Rebekah, Stefan and Klaus to get to it.
Then, the norm changed when the vampires realized that the cure could be drained from the user, thus killing the first user. However, Bonnie and Stefan were able to take a small injection of it and use it effectively, which reversed its lore completely.
The Doppelgängers
The doppelgangers, both evil and good, were the central theme of The Vampire Diaries, thus they were also subject to major retcons on the show. Initially a product of Esther's sacrificial magic which made the Originals and muted Klaus' hybrid side, the doppelganger story became something completely different as the show progressed.
Soon, Stefan also became a part of the genetic mutation, and they were then proven to be descendants of Silas and Amara, to offset their immortal lives. This twist in the tale voided everything the previous seasons had established.
Valerie As Stefan's First Love
Just when fans thought that they knew everything about Stefan's love life and interests, there was a new first love brought into the fold — Valerie. The heretic was revealed to be the first person that Stefan had been with, combined with a pregnancy arc which stunned viewers, who were sure that Katherine had been his first.
This then led to a disjointed and unnecessary rekindling of a romance that nobody was invested in. It also happened quickly, especially as Stefan was in a relationship with Caroline, which would create a further mess with a love triangle.
The First Meeting
A lot of the romance in The Vampire Diaries was dependent on who Elena met first — Stefan or Damon. The show had firmly established that Stefan had saved her life from the drowning car when the Gilberts had crashed, which was a big part of their relationship.
In season 3, it was revealed that Damon had met Elena just before the accident and compelled her to forget the meeting. He had thought that he was talking to Katherine at first. The reversal of Stefan's first meeting to Damon was a big change, but it also didn't make sense in the context of season 1 as Damon was a cold-hearted vampire. Yet, he was super nice to Elena in their first encounter, which was uncharacteristic of him.
The Reversal Of Compulsion With The Cure
The lore around compulsion and vampires who became human again was spotty and inconsistent throughout the show. In some cases, like Elena, Damon, and Katherine, the vampires turned into humans, but nobody they had compelled came forward to report their crimes.
However, when it came to Stefan, his conversion made his worst nightmare come true, and Caroline had to re-compell people to make his crimes go away. There was no clear roadmap on how compulsion wore off when vampires were cured.
Damon's Powers
The first episode very clearly alluded to Damon having higher powers, apart from just vampirism and mind control. When Elena sat in the graveyard, he could manipulate the weather around her and turn into a crow, but this was never mentioned again.
His powers were taken away just as quickly as they had been granted, and none of these supernatural abilities were ever spoken of again. Fans always wondered what a superpowered vampire would be like, but there was no opportunity to really expand on this.
Lily Salvatore's Vampirism
The matriarch of the Salvatore family was well and truly dead — until she returned. She was a vampire, just like Stefan and Damon, which didn't add up at all. Lily had a funeral, and the boys were sure she was gone, but a few details added here and there made it possible for her to come back a vampire.
Not only was she supernatural, but also the leader of a group of villainous heretics. This was also out of character for her, and the idea baffled many fans to this day.
Elena's Sleeping Curse
The very thing that was used to exit Nina Dobrev from The Vampire Diaries was retconned to bring her back in the finale — the sleeping curse placed by Kai. Her sleep was connected to Bonnie's life, which was why Elena was allowed to rest while Bonnie lived out her years.
Without much warning or preparation, Bonnie managed to find a way to break this spell that they had all collectively given up on, and the friends could then be alive and conscious at the same time. This was too big of a reversal to ignore and seemed too easy, given that Kai gave the conditions which implied breaking the curse was too risky.