Damon Salvatore was one of the best characters to come out of The Vampire Diaries. He was the brother of Stefan Salvatore, the main protagonist, and was actually the show's first villain. Despite his villainous status, however, Damon was an incredibly likeable person.
After Season 1, Damon began to redeem himself, and found himself fighting alongside Stefan and his friends, rather than against them. Although Damon finally managed to achieve peace in the series finale, he still made a lot of mistakes along the way, some of which were easily avoidable.
Damon Stole His Brother's Girlfriend
For the first six seasons of the show, there existed a complicated love triangle between Damon, Stefan, and Elena Gilbert. Originally, Elena and Stefan got together because they were incredibly likeminded and were both good people.
However, at the beginning of Season 3, Stefan went travelling with Klaus Mikaelson and so Damon and Elena were left to hold down the fort. Elena refused to stop looking for Stefan but during a particularly vulnerable moment, she and Damon shared a sweet (if not totally inappropriate) kiss.
Damon Shared His Girlfriend With Stefan
Before Damon or Stefan met Elena, they were both infatuated with her doppelgänger, Katherine Pierce. They first met Katherine when they were still human, and had yet to become vampires. Katherine was instrumental in introducing the Salvatore brothers to the supernatural.
This was because Katherine herself was a vampire. She became attracted to both Damon and Stefan and regularly slept with the two of them (though not simultaneously). Everything about this set up is just icky; no one wants to share their partner, especially with their own flesh and blood.
Damon Killed Stefan's Best Friend Because He Felt Guilty
Lexi was a brilliant character who was loved by fans so it's a shame that she didn't last very long at all. She was Stefan's best friend who turned the usually mopey vampire into a fun, happy individual, and it was clear that the two were very fond of each other.
Unfortunately, during her first appearance in Season 1, Lexi was a victim of Damon's manipulations and ended up on the wrong end of a wooden stake. To make Damon less of a monster, it later transpired that he killed her because he felt guilty, which isn't really a valid excuse.
Damon Was Controlled By The Sirens
Although this would never actually happen in real life, there is a lesson to be learnt here. In the Season 7 finale, Damon ended up under the thrall of a Siren, a supernatural creature that could control anything with her song.
In The Vampire Diaries, the Sirens were created by Cade, also known as the Devil. The Sirens were incredibly powerful and Damon struggled to break their hold over him. While he did eventually succeed, the moral here is don't let anyone influence your decision making.
Damon Left Bonnie Without Saying Goodbye
Season 7 was difficult for Damon, and not just because of the Sirens. Elena had only recently fallen into her mystical coma, and would only wake up when Damon's best friend, Bonnie Bennett, died. Damon was fiercely protective of Bonnie, but he also missed Elena deeply.
He struggled to continue on without her, and kept on making several mistakes, including not forgiving Lily before she died. Despairing, Damon decided to lock himself away until Elena woke up, but this meant never seeing Bonnie again. Damon never had the courage to say goodbye to her face.
Damon Got Rid Of His Humanity
A common theme in The Vampire Diaries was that vampires did actually possess emotions. They could love ionately, and they could hate just as equally. However, because they felt so much all at once, sometimes it was unbearable. It was then that vampires could choose to turn off their emotions.
Damon was no stranger to switching off his humanity. It was revealed that he did so when he was forced to leave Enzo behind to supposedly die in a fire, and he also turned off his emotions when being controlled by Sybil. Every single time, however, Damon regretted his actions.
Damon Pushed Everyone Away
During the first season, Damon acted as a lone wolf. This was in part due to his role as the main antagonist for the first half of the season. However, it didn't seem to be a solely villainous habit. Even when Damon was technically 'good', he still liked to isolate himself.
Whenever Damon suffered a major set back, like Elena/Katherine dumping him, he would then go on a vampire bender and deliberately hurt those who tried to help him. If you're hurting, and there are people who want to help you, let them.
Damon Took His Anger Out On Other People
Damon is probably one of the best vampires in television history. He was suave, funny and unbelievably charming (when he wanted to be). However, he also had a dark side.
Part of his anger stemmed from the fact that he never truly wanted to become a vampire. The only reason he wanted to live forever in the first place was to be with Katherine. However, she 'died' before Damon changed. Part of Damon is angry about the fact that he wasn't given a choice and so he took his anger out at Stefan.
He Challenged Powerful Serial Killers
In Season 6, Damon was stuck with Bonnie in a 'prison world', a sort of alternate reality built by the Gemini coven to contain the villainous Kai Parker. Kai was brilliant as an antagonist. He was charming, entertaining to watch, but could be incredibly menacing.
Given that Kai had spent a long, long time on his own, the fact that he now had Damon and Bonnie as playthings made him a lot scarier. Damon, on his part, decided the best course of action was to rile the psychopath and taunt him.
Damon Always Acted Rashly
Damon was never known for his calm and rational behavior. In fact, the opposite could be said to be true. Unlike his brother, Damon was not the most patient person ever and usually adopted an act first, think later policy.
This kind of thinking usually wound up making Damon's mistakes a whole lot worse. If some had hurt him, he would lash out without thinking. Equally, if someone had gotten on his bad side, he would generally try to unleash all manner of Hell before calming down.