Mind Compulsion is an ability exclusive to the original vampires, immortals, vampires, witches, and hybrids. It allows the user to control another person's mind by making eye contact, somewhat astral project into their dreams and overall erase the victim's memories or even alter them to the point where something is completely different about them. Compelled beings usually follow the instructions given to them by the vampire who compelled them to the best of their ability, sometimes even those that would otherwise be beyond their "normal" capacity (i.e. being forced to forget a very recent and otherwise unforgettable experience, cause them to develop new skills, and even create new personalities). Needless to say, this ability plays a vital role in keeping the existence of Vampires (and by extension, other supernatural races) hidden. While most vampires use compulsion with verbal commands, this is not heeded as a necessity, as in one such instance Damon was able to compel Caroline with eye contact alone. However, this method of compulsion has not been used since. Silas however seems to easily do these feats without eye contact or verbal commands when he wants, and can even get into the minds of the Originals.
Vampires can only compel humans, while Originals can compel both humans and vampires, but not their fellow Originals (as Rebekah pointed out to Kol); and though Vampires seem to be aware that they are being compelled while under the effect (Humans aren't), they are, by no means immune to it, unless they have Vervain in their system. However, any vampire can control the dreams of another vampire, like Katherine did to Stefan and Elena and what Damon did to Rose. Compulsion doesn't work if the victim is on vervain. In spite of that, Silas was able to entrance Caroline with a unique form of the skill
When someone is compelled, a new compulsion cannot override a previous compulsion. It is, however, possible to plant a new compulsion for so long as it does not conflict with the previous one. As users grow older, their mind compulsion skills evolve and mature. To prevent compulsion, Elena wore a pendant which contained vervain, and Jeremy was also given a bracelet with the herb in it.
Compulsion seems to be tied to the user's spiritual essence, since Klaus was able to use it while inhabiting the body of Alaric, a Human.
Both of them also drink vervain tea. When a human who has been compelled in the past dies and is in transition to a vampire, they will remember everything they were compelled to do or forget.
As Silas created the Immortality Spell for himself, and the fact he was a powerful psychic, the mind compulsion could come from Silas' original spell, to strengthen his psychic powers, and is why it would be present in the Mikaelson families version of his spell.
It is discovered that Bill Forbes cannot be compelled as he stated to Damon in Disturbing Behavior, and he said "it's a sort of human focus he's been honing for decades", so there is a possibility all humans could resist even though it could take a long time.
Due to Damon's age and experience, he has become relatively good at using compulsion. His first known use of the ability is for good, rather than evil, as we see him sending away some guests of Stefan's who have been lured into the Salvatore Estate so that he can feed. This occurs in the Salvatore brother's first few weeks after becoming vampires. As Damon got older, he used the skill more efficiently, however this was not always for good, and often was used as a sadistic hunting skill. Damon is known to have tormented Stefan's dreams on some occasions, leading him to believe that he (Damon) was feeding on Elena. Damon provides some of the best examples of the correct use of compulsion. He can be seen in the series erasing Jeremy Gilbert's memories in order for him not to feel the pain and grief. As a result, Jeremy is seen to have a happier demeanor, be working harder in school, and is no longer is involved with drugs. The most notable example of Damon's compulsion failing is when Bill Forbes is able to resist simply by practicing the skill for decades. Bill stated that he believed Damon's technique to be 'sloppy', however this is more likely to have been an insult, rather than a neutral observation. Despite this weakness it should be noted that Damon has so far been the only vampire so far to compel a human without any verbal commands. This was done after Caroline freed Damon from the Salvatore Dungeon and made Caroline forget the incident and act nice to him.
When Stefan first turned into a vampire it is likely that he was quite skilled in regards to compulsion. This is due to the excessive amount of human blood he was drinking at the time. As a result of Stefan changing his diet from human to animal blood, his ability to compel was weakened to the point that it almost diminished. An example of this is when he compels Vicki Donovan to forget that Damon attacked her. In the scene, Damon asks Vicki to think carefully about what had happened to her, and she soon figures out that she had not been attacked by an animal, but by the eldest Salvatore brother. Stefan's, and arguably all vampires’, ability to compel relies solely on the diet which they are consuming. Stefan's compulsion is clearly at its best when he is feeding on human blood. There are many examples of this, most notably, when Stefan was a ripper in the 1920s, and when he had just turned.
Katerina is arguably one of the more skilled non-Original vampires when it comes to compulsion. This is mainly due to the fact that she is over 500 years of age and has been taking small amounts of vervain for over 145 years. She is first seen compelling Stefan Salvatore in a flashback, where it is also revealed that she is compelling Damon. Both Salvatore brothers, at the time, were human. Katherine frequently uses compulsion for evil, her most notable uses of the skill being when she compels Matt Donovan to get Tyler Lockwood drunk so that he kills another person, triggering the werewolf gene. Another notable scene that shows Katherine using compulsion is where she compels Jenna to stab herself in the stomach, resulting in her hospitalization. Katherine is also very clever when using her compulsion, wording her commands carefully to fit her needs. She recently compelled an entire town to forget who she was unless they were talking directly to her. At which point they remembered every interaction that they had with her. This isn't fool proof however as Elena looks identical to Katherine and the compelled humans did not know that they were different people and were able to remember everything.
As Caroline has only recently turned into a vampire, her experience with compulsion is not at the level of many of the other vampires seen in the series. Caroline can be seen using compulsion on her first day as a vampire. As a result of her vampirism, her senses and feelings are greatly heightened. It is because of this that she snaps at Aimee Bradley who was supposedly flirting with her boyfriend Matt Donovan. Perhaps the most memorable time that Caroline uses compulsion is when she attempts to erase Matt's memories with the hope that he will forget that she is a vampire. As Matt was drinking vervain, he was immune to the compulsion, and therefore remembered everything.
Elijah is highly skilled where compulsion is concerned, due to the fact that he is an original, and being the second oldest vampires to ever exist. He is able to compel both vampires as well as humans, making him all the more powerful. There have been countless occasions where we have seen Elijah use his compulsion, though more memorable scenes include when he compelled Slater, Rose, and Katherine as they are all vampires.
Unlike his brother, Elijah, Klaus was much more violent in the way he compelled someone. He liked to torture the victim almost every time. The most notable time he compelled someone was when he compelled Katherine Pierce, by getting her to stab herself in the leg multiple times with a knife. He used it mostly on her throughout his time on screen, such as compelling her not to leave Alaric's Apartment. He also "compelled" Katherine to take the werewolf venom cure to Damon but Katherine was on vervain and immune, though Klaus was seemingly aware of this. Klaus also forced Stefan to do everything he says and one of his commands was to turn his humanity off which included any feelings he had for Elena, however, Stefan managed to resist his compulsion which forced Klaus to compel him again.
As Tyler became a hybrid, he gained all the gifts of a vampire, while still retaining the abilities of a werewolf. His first mind compulsion took place at the track field, where he compelled his coach to stop their training. Tyler is shown to be very aggressive, yet skilled, at compelling others.
Mikael was an Original who was very skilled at compulsion. He was able to at least partially undo Klaus' compulsion on Stefan, albeit through threat of physical harm and finding loopholes. He was also the first vampire to compel hybrids.
During the funeral, April Young is badly injured by Connor in order for him to find vampires. Elena uses her mind compulsion to prevent April from talking about what happened. Elena in episode 4x05 makes two compulsions in Frat House.In episode 4x17 she is a compulsion on a woman at the Billy's Bar telling her not to move and not to shout or speak. In the episode 4x19 she compelling the owner of the store dressed in Mystic Falls to steal the dress Caroline. In the 5x05 she compelling Aaron for information about him and then obliges him to forget.
Rebekah used compulsion to get what she wants, just like her half brother Klaus, for example in After School Special she compelled Stefan, Elena and Caroline to tell her the information about the cure and to get Elena to confess to Stefan about how she really feels about Damon. She also compelled Tyler to turn into a Werewolf making her the second vampire ever to compel a hybrid.
Kol Highly skilled compulsion is concerned, due to the fact that he is an original vampire and being one of the second oldest vampires to exist he is able to compel humans and vampires. He attempted to compel the information about the cure out of Atticus Shane, however, Shane was immune. He compelled Damon to stab himself with little effort and didn't need to look directly at him. He also compelled Damon to kill Jeremy, too.
- Vervain: Vervain makes the victim immune to the compulsion.
- Original Neutralizing: If an Original is neutralized with the white oak ash dagger, any compulsion they have used on a vampire will be negated; this principle applies if an Original is revived by the dagger being pulled fully out of the heart.
- Limitations: Mind Compulsion is limited and can only be used against humans, and vampires in the case of Originals. Other supernatural creatures such as werewolves and witches are immune to mind compulsion. Hybrids can be compelled by Originals due to the fact they are half vampire. Furthermore, it only seems to work via eye contact, and at a very close range, though more proficient users can perform it at a limited distance away from their victims, as almost every compulsion performed so far has occurred with the vampire using compulsion having their head right next to their victims as they compel them.
- Previous Compulsion: A vampire cannot undo the compulsion of someone who has already been previously compelled through a new compulsion. This also applies to Originals. Presumably, this also applies to hybrids.
- Transitioning: After a human turns into a vampire, the compulsion wears off and the human begins to remember everything that was erased from their minds.
- Loopholes: Since Compulsion works by causing the recipient to be subserveint to the commands issued to them by the Compeller, and that the Compeller can only issue any number of commands at any given time, it is possible to find flaws in the compulsion by exploiting loopholes.
- Mental Resistance: The humans with great mental strength can withstand, and void the compulsion, however, few humans who have this ability, since the charm and sensuality of vampires makes it difficult to resist the compulsion
- The Brotherhood of the Five: The Brotherhood of the Five can not be affected by vampire, Hybrid, or even Original compulsion.
- Magic: A witch is capable of delving into the mind of a being after removing the compulsion, however the process is extremely painful