The Originals has no shortage of intelligent characters whose calculated or impulsive decisions moved the plot along in intriguing ways. But as the seasons went on, it became clear that all it takes is one wrong choice for their lives to fall apart. The series was not afraid to put the main characters in danger nor was it hesitant to kill them off.
Whether they had pure intentions that went sideways or if the decision at hand was but a foolish mistake, each character made at least one bad decision that had catastrophic effects.
Rebekah Mikaelson: Calling Mikael
In 1919, Rebekah and Marcel were in love and they were one of the best couples in The Originals. But Klaus didn't allow them to be together, so she came up with a plan to get him to leave New Orleans. She had a witch inform Mikael of their whereabouts knowing that he would try to kill Klaus. However, their plan backfired as Mikael attacked Marcel and all of the Mikaelsons were forced to flee the city.
Klaus didn't find out about his sister's betrayal until the events of season 1 and it drove a wedge between them. This was clearly Rebekah's worst decision as Klaus had given her and Marcel his blessing mere days before Mikael's arrival, rendering their plan pointless.
Marcel Gerard: Challenging The Originals
The feud between Marcel and the Mikaelsons was one of the biggest recurring tropes in The Originals and it was most prominent in season 1. There were several episodes centered around Marcel rallying up his vampires against the Mikaelsons and most of the time their fights would not end well for him.
First, he planned on subduing Klaus who ended up winning the fight, killing many of Marcel's vampires in the process. Another time, he broke the treaty between the vampires and the witches, which resulted in Elijah killing his right-hand man, Thierry, in retaliation. Finally, he led his people in a fight against the Mikaelsons, in "The Battle Of New Orleans" where the vampires that weren't killed by Elijah were bitten by the Guerrera werewolves. As a result, he lost most of his comrades in battle.
Hayley Marshall: Trying To Run From Dahlia
In the second season, the Mikaelsons are faced against Dahlia, an incredibly powerful witch (and one of the best villains in The Originals) who was after baby Hope. At first glance, running might have seemed like a good choice. Hayley was willing to do whatever it takes to save her daughter so she decided to take her werewolf pack and leave in an attempt to escape.
But considering that they were up against a seemingly omnipotent witch who was over a thousand years old, then maybe leaving on foot wasn't the best idea. Not only this but halfway through their escape route, they decided that Aiden deserved more than an ordinary burial so they went back to New Orleans to throw a funeral for their fallen pack member. And this only made it easier for Dahlia to catch up to them.
Cami O'Connell: Trusting Her Dark Objects Over Klaus
When Cami turned into a vampire she had a hard time coming to terms with it. She didn't trust Klaus, instead, she was determined that her dark object would be enough to protect her and she made some foolish decisions in an attempt to retrieve them. She stole the last remaining piece of white oak and it was inevitably stolen from her by Aurora who almost succeeded in killing Elijah with it.
But this wasn't the only time she refused Klaus's help. Even after Lucien turned into an upgraded original vampire, Cami refused to stay with the Mikaelsons in the secured compound, choosing instead to go back to her apartment with her dark objects. This was a bad decision, as it made it easier for Lucien to find her and kill her.
Freya Mikaelson: Destroying Davina
After Kol killed Davina under the ancestors' influence, he and Marcel were determined to bring her back. With Freya's help, they came up with a plan to rescue her spirit from the ancestors and buy time until they found a way to resurrect her. However, with Lucien threatening her siblings, Freya needed to channel the ancestors' magic to revert his transformation and take away his power. To do that, she had to use Davina as a conduit, leaving her in the ancestors' mercy and destroying her chance for resurrection.
This decision had a domino effect that led to the fall of the originals at the end of season 3. Killing Davina turned Marcel, Vincent, and Kol against them. It served as a motive for Marcel to turn into the same creature as Lucien and use his new powers to put down the Mikaelsons.
Davina Claire: Assassinating Witches
After Davina became the Regent of the nine covens of New Orleans, she faced opposition from some witches that didn't want her as their leader. Following a threat against her life, Davina manipulated Hayley into assassinating the witch responsible. However, that backfired as it led to the "ninth ward massacre."
When Davina's actions came to light, the witches turned against her and shunned her. As a result, she lost her connection to the Ancestors which was her main source of magic.
Vincent Griffith: Practising The Hollow's Magic
Prior to the events of the show, Vincent was happily married and a father-to-be, living in New Orleans under Marcel's control. He became determined to find a way to defeat Marcel and make the city safer for witches which led him to make some questionable decisions.
One day he discovered a mysterious notebook filled with ancient sacrificial magic that he had never seen before. He studied and practiced the magic within it, not knowing its evil origins. Even though he knew the dangers of using dark magic, he shared The Hollow's power with his wife Eva. She was soon enraptured by it, causing her to lose herself in it. She began sacrificing children for The Hollow and Vincent was forced to take her to the Fauline Cottage.
Elijah Mikaelson: Erasing His Memories
At the end of season 4, each Mikaelson sibling took on a piece of the Hollow, an ancient dark magic that was threatening Hope's life. Because of that, they all had to scatter around the world and stay as far away from each other and from Hope as possible. But Elijah didn't think that he would be able to go against the Mikaelson vow to stay together "always and forever," so he asked Marcel to erase his memories.
But he didn't only forget his vow. Instead, Elijah erased a thousand years' worth of memories, including all the enemies he made in his long life. As he wasn't able to recognize his enemies, he unknowingly sided with them against the people he truly loved, and that had catastrophic effects, resulting in Hayley's tragic death. His decision was entirely unnecessary and fans thought that there were much better solutions, as he could've easily asked Marcel to compel him to stay away instead.
Klaus Mikaelson: Cutting Ties With Hope
After taking on a piece of The Hollow, Klaus had to stay away from his daughter for her own good. The two of them were keeping contact through letters and phone calls until one day, Hope tried to visit him through an astral plane and accidentally witnessed him murdering someone. Horrified that she saw his true colors, Klaus decided to cut all ties with her, thinking that she would be better off without him.
This was Klaus's biggest mistake because it went against everything his character arc was building towards. Klaus had spent the whole series struggling with his fear of failing as a father and instead of trying to be better, he gave up and let his fear become true. Not only this, but it also led Hope into making some terrible decisions too.
Hope Mikaelson: Kidnapping Hayley
Everyone makes mistakes in their youth, but some mistakes have greater effects than others. At the beginning of season 5, teenage Hope is angry and sad about her father leaving and cutting all contact with her.
In an attempt to draw Klaus back to New Orleans, she put a spell on Hayley to keep her asleep and fake her kidnapping. Even though her plan worked and Klaus came back right away, it quickly went sideways. As she was incapable of defending herself under Hope's spell, Hayley was taken by Greta. Not only this but the cloaking spell Hope cast on her mother made it impossible to track her down with magic. Klaus did everything he could to rescue Hayley but by the time he found her, it was too late.