Damon Salvatore is a character that viewers either love or hate. He was the main antagonist in The Vampire Diaries when he was first introduced, but after he fell in love with his brother's girlfriend, he slowly became less of a villain and more of an ally. However, his actions were morally grey and not everyone believed he was truly a changed man.
While Damon started making better decisions once he met Elena, he continued to lash out at people depending on his emotional state. Damon was a hit or miss depending on the season, and his character development was more of a rollercoaster ride than a gradual improvement.
He Tried To Control Elena
One of the reasons Elena picked Stefan over Damon for so long is that Stefan let her make her own decisions. Damon would always do what he thought was best for her, even if it wasn't what Elena wanted.
Elena had a habit of putting herself in harm's way, and even though Damon was acting in Elena's best interests, he didn't have the right to control her. After Katherine came to town and messed with Damon's head, he was convinced Elena had feelings for him and forcibly kissed her when she tried to fend him off.
He Promised Stefan An Eternity Of Misery
Stefan isn't a saint when it comes to his relationship with Damon. He didn't want to be immortal without his brother, so he forced Damon to feed and turn into a vampire. In retaliation, Damon promised Stefan an eternity of misery, and for the most part, he stayed true to his word. There's no excusing Stefan's actions, but what he did came from a place of fear and love.
Damon's anger is understandable and everything he did to torment his brother came from that place. The brothers' love for each other won out in the end, and Stefan sacrificed his life to save the town and make Damon human again. But the two missed out on over a century together due to Damon's inability to take the high road.
He Killed Jeremy
Damon's lucky that Jeremy was wearing his Gilbert ring because he and Elena might have never ended up together if he hadn't been. Hurt by being rejected by Katherine and Elena in the same night, Damon once again had the urge to lash out.
When Jeremy came into the room to check on his sister, Damon snapped his neck and killed him. It was obvious that Damon immediately regretted what he did, but Elena never would have forgiven him if Jeremy hadn't come back to life. No one should have to consider the safety of their brother when telling a man "no."
He Abused Caroline
Caroline's hatred for Damon was well-earned given that he treated her like a toy. When Caroline discovered Damon was a vampire she tried to get away, but Damon used compulsion to make her stop fighting.
He then continued a sexual relationship with her, which clearly wasn't consensual, and used his mind control to leave Caroline in a state of constant confusion. Damon used her as his own personal blood bag and tried to kill her while she was a human, and again after she turned into a vampire.
He Punished Elena For Their Breakup
Season 5 of The Vampire Diaries proved that Damon hadn't changed. He kept himself in check in order to be with Elena, but all it took was one misstep to set him off. When Katherine pretends to be Elena and breaks up with Damon, he decides to punish her for her choice.
He and Enzo blackmail Bonnie and threaten to kill Jeremy, and Damon even kills one of Elena's friends to send a message. Elena did love Damon, but if she ever decided to break up with him for real, the lives of everyone she loved would be in jeopardy.
He Killed Stefan's Best Friend
Stefan and Lexi met shortly after Stefan became a vampire, and she was the only person who was able to stop Stefan from feeding on people and help him gain control of himself. Lexi was there for Stefan when Damon abandoned him, and he never would've been able to give up human blood without her.
But Damon made it his life's mission to take away everything that made Stefan happy, and he murders Lexi in front of Sheriff Forbes in order to gain the trust of the council. Killing Lexi, especially after everything she did to help, was an unforgivable crime.
He Force-Fed Elena His Blood
Damon continuously puts his own wants and needs above Elena's. Elena was willing to take a chance on Elijah's elixir in the hopes of staying human, but Damon wasn't on the same page. He force-feeds Elena his blood to make sure she'll come back to life, even though she'll be a vampire.
When Stefan tries to save Elena, Damon stabs his brother in the stomach and leaves. Jon sacrificed his life for Elena to remain human, but that's something he shouldn't have had to do in the first place.
He Left Enzo
Damon and Enzo were kept as prisoners and tortured for years, causing them to seek solace in each other. Their cells were side by side and their conversations were what kept them from going insane.
The two plot an escape, and Enzo gives Damon all his blood rations to help him build his strength. When the time finally came to make a run for it, Damon is unable to save Enzo and he leaves his best friend behind to die. He turned his emotions off and never looked back.
He Betrayed Bonnie
Damon and Bonnie's friendship was a surprising highlight of The Vampire Diaries' later seasons, which made Damon's treatment of her all the worse. Bonnie sacrificed herself to free Damon from the prison world, and when she returns, one of the first things he does is break her trust.
When Damon needs something from Kai, he asks Bonnie to give him the chance to apologize for his actions. Bonnie refuses because of all the torture Kai put her through, so Damon and Kai ambush her. Bonnie is shaken from seeing the man who traumatized her, and heartbroken that her best friend would be so cruel.
He Hid His Kills From Elena
Elena was under the impression that Damon stopped his murder sprees after they got together, but that wasn't the case. Damon made a pact to kill the descendants of everyone who had tortured him and snuck out of town to murder an innocent girl.
It exemplified that Damon was the same person he had always been, the only difference being that he hid it from Elena. Redeeming a character who was given the chance to change over and over again, but never did, feels forced rather than earned.