The Vampire Diaries had plenty of plot twists but some of the most shocking moments were early in the series when storylines were at their peak and changing things up was a welcome experience. As time went on, though, some of those major changes became expected or repetitive, and they lost their excitement along the way.
By using many storylines too often, they became tired as the audience had already seen these events play out, and everyone knew it was only a matter of time before things went back to normal. Some events happened so often they occurred with nearly every character, such as vampires flipping their humanity switch. In other cases, popular young adult tropes would appear and remain for long periods of time, such as the love triangle.
Stefan Becoming A Ripper
Originally introduced in season 1, Ripper Stefan was the human blood addict version of the normally controlled vampire. Stefan's addiction to human blood was the reason why he usually stuck to animal blood. But, when his wish to drink in small doses to become stronger and not go overboard doesn't go according to plan, it shows a much darker side of Stefan's vampirism. While Stefan does gain control again, his ripper side reappears when Klaus forces it out of him, playing off Ripper Stefan as one of season 3's antagonists.
While exciting to see a darker side of Stefan, The Vampire Diaries pulled Ripper Stefan out of the vault in seasons 6 and 8 as well, making it occur too many times to remain intriguing as the audience already knew the capabilities of a humanity-less and bloodthirsty Stefan.
Vampires Flipping The Humanity Switch
All the vampires got a chance at this at least once. Vampires have the ability to turn off their emotions, allowing them to do whatever they want without feeling the guilt and consequences. Damon turns off his humanity to walk away from Enzo during a fire. Klaus and Caroline have each forced Stefan to flip his switch at different points. Elena turned off her humanity after Jeremy's death, while Caroline flipped her switch after Liz ed away.
While they each had a different experience, flipping the humanity switch usually results in the character becoming mean, uncaring, and an annoyance for everyone else to deal with.
Doppelgängers Popping Up Everywhere
If Elena and Katherine had been the only Doppelgängers, this would not have been an issue. Both were well-developed and intriguing people with enough differences and grudges to keep their interactions exciting.
By giving Stefan a Doppelgänger, too, with Silas and Tom Avery and other Petrova Doppelgängers like Tatia and Amara, it all became too much. Doppelgängers or their blood became the solution to far too many magical problems.
Elena Needing To Be Saved
Usually, if someone needs to be saved, it's likely Elena. By being a Doppelgänger, she is the key to numerous magical problems. She is also a guarantee to get Stefan and Damon's attention.
While Elena does eventually learn to fight for herself, she still is saved more often than she saves herself. Sadly, Elena's family and friends would often have to make large sacrifices to save her life.
Way Too Many Love Triangles
The Vampire Diaries Universe is filled with love triangles. At first, it began simply enough by suggesting that Stefan and Damon had fought over Katherine in the past. But, by the first season's end, there was already another one in the mix between Stefan, Elena, and Damon. This is by far the biggest love triangle in the series as it is acknowledged or continues for five seasons before it finally dies, with Elena and Damon coming out the victor.
But, there are still more. Caroline ends up in what fans determined to be a triangle between her boyfriend Tyler, and Klaus, with who Caroline shared an unlikely connection.
Bonnie Is Separated From Everyone Else
Bonnie goes through some of the biggest hardships of anyone yet continues to be one of the most self-sacrificial. Bonnie revives Jeremy at the price of her own life. While she is stuck on the Other Side, Elena and Caroline carry on with their lives, waiting for their friend that will never show up. When Bonnie does have the chance to return to the living as the anchor, it is only for a limited time, as when the Other Side begins to deteriorate, Bonnie will go with it, except instead of falling into oblivion, she and Damon end up in a 1994 prison world together.
But, after a few months together, Bonnie sacrifices herself so Damon can escape leaving her alone with Kai until he escapes as well, leaving Bonnie all alone. Bonnie spends months alone until she discovers the way out and saves herself.
Coming Back From The Dead
Regardless of if someone transitions into a vampire, returns as a ghost, or is literally resurrected, coming back from the dead was a constant element of The Vampire Diaries. Pretty much everyone did not stay dead for long, especially if they were a central character.
Even Lexi returned numerous times as a ghost after Damon killed her. Alaric, Tyler, Bonnie, and Jeremy were also all resurrected to the living at different points.
Transitioning Into Something
Whether it be a vampire, a werewolf, a hybrid, or something else, the main characters did not stay human for long. Everyone other than Matt experienced being some sort of supernatural being. Tyler experienced it three times, with his first werewolf transformation, becoming a hybrid, and then he triggered his curse a second time, killing Liv.
Elena, to her horror, became a vampire after drowning with Damon's blood in her system. Katherine turned Caroline into a vampire. Jeremy became one of the Brotherhood of the Five. The list goes on and on.
Characters Betraying Each Other
Betrayal tends to be one of the biggest elements of the series. Elijah betrays Elena and her friends when he chooses to save Klaus during his werewolf transformation instead of killing him like Elijah had claimed he wanted to do.
The Salvatore brothers have also betrayed each other regarding Katherine or Lexi. Klaus had turned on his siblings and daggered them countless times.
The World Is Threatened To End
Mystic Falls faces the possibility of destruction or major change many times. The world's end is a popular trope in dystopian or fantasy fiction and is either the catalyst of events or what everything is building towards. Mystic Falls has been the setting of many spells that have helped or hurt the supernatural and humans.
However, the series finale features the worst of all. With Hellfire approaching and threatening to kill everyone in its path, Bonnie steps up to save the day, gaining power from her Bennett ancestors. Bonnie's heroic moment saves Mystic Falls and all its residents from death.