Passenger

“	Hello, Matt Donovan. I'm the passenger inside you. I know you have many questions, but all you need to know is that one day my friends will come looking for this blade. Protect it at all costs...or this will be your throat.	”
	— Gregor using Matt's own body to talk to him in For Whom the Bell Tolls

A Passenger is the spirit of witch, traditionally a Traveler, who lays dormant inside another person's body until activated by a magical code word or incantation. According to Katherine, they lay dormant like parasites inside the body of their host until activated. Passenger spells are primarily used by the Travelers as a way to possess other bodies without facing the consequences of their Travelers' curse while practicing magic as a group in their own bodies.

Creation

To become a Passenger, a Traveler witch must speak the incantation "Jaryakat a zem, daryeet acza" while holding the head of the person they wish to possess in their hands. The recipient's eyes will then gloss over black, confirming the transfer. Passengers can take permanent control of their hosts bodies. In order for this to happen, the body of the Passenger and some blood from the host is required before a ritual is performed and the body of the Passenger is burned.

History

Season Five

In I Know What You Did Last Summer, Nadia lured Matt into an alley and returned the Gilbert Ring that she had stolen from him over the summer, distracting Matt and allowing her boyfriend, a Traveler named Gregor, to cast the Passenger spell on him.

In True Lies, Nadia killed Gregor in front of Silas to convince him that she was a trustworthy person with whom to work. However, Gregor's spirit lived on in Matt's body, which he used to continue his and Nadia's plans, though his control over Matt's body was sporadic and dependent on his spirit being summoned by others using the code words.

In For Whom the Bell Tolls, Matt, worried about his recent bouts of losing time, installed cameras in every room of the Lockwood Mansion to try to figure out what he was doing while he was blacked out. When he later watched the video footage, he was shocked to see himself taking out an unfamiliar knife on camera. It is revealed that Gregor, in control of Matt's body and speaking with an accent, was aware of the camera, and spoke into it to pass on a message to Matt once he was conscious-- that the blade in his hand was to be protected at all costs until his friends came for it. He then proceeded to slice Matt's palm open to demonstrate what will happen to him, should he lose the knife.

In Dead Man on Campus, Katherine asked Matt to bring her Gregor's blade, and when she revealed to Matt and Stefan that Gregor was a Traveler who had taken possession of Matt using a Passenger spell and forced Gregor to admit his orders (to kill Silas, and then to kill Katherine), she stabbed Matt with it, killing Gregor's spirit and leaving Matt unharmed.

In Fifty Shades of Grayson, Nadia wanted Katherine to become a Passenger in someone else to prevent her inevitable death from old age as a result of taking The Cure. Katherine, however, reminded Nadia that she had never used Traveler magic before, as her father had referred to it as "the devil's work" and refused to allow their family to practice it. However, after a heartfelt moment with Stefan, Katherine decided to do the Passenger spell after all, but had a heart attack and collapsed at the boarding house before she had a chance to do it.

In 500 Years of Solitude, Katherine, after having been brought back to the boarding house after Stefan compelled the hospital to release her, was visited by Nadia and her Traveler associate Mia to teach her the Passenger spell so she could cast it before she died. Though Katherine made a big show of refusing to possess her own daughter so she could continue to live, it was later revealed that she always intended to go through with the spell, only instead of possessing Nadia, she cast the spell on Elena when she came to her bedside to say goodbye before she died. Once settled in Elena's body, Elena was called by Nadia, who had Mia say the incantation to bring Katherine's spirit into control of her body.

In The Devil Inside, it was revealed that that there is a spell that gives a Passenger permanent control over their host body. However, it requires the blood of the host and the burning of the body of the Passenger, preventing them from ever returning to their original bodies. Mia once again helped Katherine complete the spell, and though Elena came back into control midway through and tried to intervene, Mia was able to complete the spell before Elena could alert anyone to what had happened, making Katherine permanently in control of Elena's body.

In No Exit, Caroline and Stefan realized that Katherine was a Passenger in Elena's body.

In Gone Girl, Stefan used Gregor's blade to kill Katherine and return Elena's spirit into control of her own body.

In Resident Evil, Liv revealed to Tyler, Jeremy, and Matt that her coven had been tracking the Travelers for centuries, and explained that several times in the course of history, the Travelers convened together in various towns by slowly casting Passenger spells on the townspeople so that they wouldn't trigger any complications as a result of their Curse. She then enlisted their help in using Gregor's Passenger-killing blade to free the affected townspeople from the Passengers' control. In his search, Tyler discovered that Liz Forbes had been possessed by a Passenger, and he stabbed her with the Passenger-killing knife to free her. However, he was caught with the knife by Julian, another Traveler, who decided to be a Passenger in Tyler's body. Once he was possessing Tyler, he turned over Gregor's blade to Markos, who destroyed it, ensuring that the Passengers could not be killed without also killing their hosts.

In Man on Fire, the Travelers convened to test a theory Markos had involving the combined blood of the last male and female doppelgängers of their respective lines. In order to do this, Markos used the blood of Tyler, whose body was still being possessed by Julian, and who was locked up to prevent Tyler from regaining control and fleeing, to turn Sloan into a vampire. Once she had turned and transitioned, she was fed the combined doppelgänger blood, which cured her of her vampirism before returning her to the state she was in before she was turned-- dead with a slit throat. Thrilled that his experiment worked, Markos explained to the rest of the Travelers that they were not only close to breaking their curse, but also in bringing upon them the end of Spirit Magic and everything it had created, including vampires.

In What Lies Beneath, Tyler's spirit regained control of his body while Maria, the wife of Julian, was trying to have sex with her husband. Tyler became aware of the fact that most of the other Travelers had become Passengers in the citizens of Mystic Falls, and managed to purposely transform into his wolf form to prevent Maria from calling Julian's spirit into control of his body. He ran straight to the Salvatore Boarding House, where he convinced Matt and Jeremy to lock him up in the cellar to both prevent Julian from being able to return to the Travelers and to torture Julian into telling them what the Travelers were planning. Meanwhile, at the Traveler camp, Markos was so angry at Maria for letting Julian/Tyler run away that he ordered her to go to the cave where all of the Travelers' original bodies were being kept and perform the spell on his body that would make his possession of Tyler permanent, knowing full well that this was essentially a death sentence for Julian once their Magic Purification Spell brought the end to all vampiric creatures.

In Promised Land, the Travelers, all of whom were Passengers in the bodies of dozens of Mystic Falls residents, went to the Town Square to perform the Purification Spell, which involved them crushing vials of doppelgänger blood in their hands as they chanted the incantation. Afterward, the Travelers whose original bodies were still alive were able to return to them, where they were being kept in the Salvatore Boarding House by Damon.

Powers and Abilities

Possession: Passengers have the ability to take control of another being's form by placing their spirit into the body of another.
Mental Resistance: Passengers render their host body immune to certain mental powers, such as telepathy and mind compulsion due to the presence of two minds in one being.
Witchcraft: Passengers, being Travelers by default, are able to perform magic and cast spells in their host bodies so long as they are human.

Weaknesses

Activation: Once the Passengers lose control of their host bodies, they return to being dormant and cannot regain control of their hosts unless the host bodies hear the activation or summoning word, Vyjdi, or Vyjit or the spell to render the possession permanent is performed.
Supernatural Hunters: Members of the Brotherhood of the Five are said to be immune to mind control (compulsion, psychic powers etc.). According to Liv, this includes possession by Travelers.
Magic: Passenger are susceptible to the powers of witchcraft. This is inclusive of mystical objects such as the Gilbert Device, Papa Tunde's Blade, and Dark Objects. It is unknown if a Siphoner can siphon the magic from a passenger.
Mortality: Passengers who possess humans share many of the same weaknesses as non-supernatural beings (e.g. old age, suffocation, broken neck etc.).
Time: Unlike most forms of possession, a Passenger can only remain in control of the host for a limited time. The duration of the possession is apparently not the same for all species, since the Travelers were wary of Julian after he Passenger-ed himself into Tyler's body, suggesting that Passengering into a hybrid's body was unprecedented, likely due to their short history as a species and hybrids being the most physically powerful supernatural species on earth.
Traveler Knife: Passengers are vulnerable to a magical blade capable of dispatching them from their host's body and killing their spirits without harming or killing the host.
Lycanthrope Transformation: As demonstrated by Tyler, his transformation into his wolf form allowed him to resist the activation of a Passenger by another Traveler, suggesting that Passengers can only take control of humanoid species rather than animalistic ones. Presumably, this may also mean that the same could be said to a normal werewolf harboring a Passenger within themselves prior to a full moon.
Physical Contact: The initial possession requires touching the temples of the host body.

Known Passengers

Gregor - possessing Matt Donovan's body
Katerina Petrova - possessing Elena Gilbert's body
Julian - possessing Tyler Lockwood's Body
Unknown Traveler - possessing Elizabeth Forbes' Body
Carl - possessing Pam Douglas' Body

Gallery

Trivia

The spell which the Travelers use to become Passengers is referred as "Passenger Spell" by Nadia and Katherine.
The language that the Passenger spell and the activation word to summon the Passengers are spoken in is Czech.
Jet-black eyes appear to be the main feature of Passengers, as the eyes of a Passenger host would turn black when the Passenger spell is completed and whenever the control of the body is switched between the host and the Passenger.
Passengers can take permanent control of their hosts bodies, but only if additional spells are performed to grant them such control.
There are some similarities between Passengers and demons of Supernatural
- Eyes of Passenger Hosts turn Jet-black which is the same eye color most demons of Supernatural displays from the humans they possess
- The possession theme of the Passenger spell and the fact that it could be countered using a mystical blade is similar to the demons of Supernatural. The only difference being, the Traveler knife doesn't kill the host, while the one from Supernatural typically does, if it is used to stab a vital area of the body such as the chest or the abdomen.
It was revealed by Markos in Resident Evil that the true purpose of the Passenger spell is to circumvent a curse which would wipe out the Travelers if they are to assemble in one place in their own bodies. By taking over other people's bodies and gathering in one place as Passengers, they would not trigger the curse.
There was only one blade known which could kill Passengers permanently and remove it from the host's body. This blade belonged to Gregor, and was used three times to kill Passengers before it was destroyed by Julian and Markos in Resident Evil. The first time, it was used to kill Gregor's spirit inside Matt Donovan in Dead Man on Campus; the second time, it was used to kill Katherine Pierce's spirit inside Elena Gilbert in [Gone Girl, and the last time it was used to kill an unknown Traveler's spirit inside Liz Forbes' body in Resident Evil.
The Passenger Spell can be used by Travelers to put their spirits in vampires and hybrids, as shown by Katherine when she performed the Passenger spell on Elena in 500 Years of Solitude, and Tyler when he was possessed by a Passenger named Julian in Resident Evil. It has not been revealed if Travelers can transfer themselves to other supernatural beings such as Werewolves and Witches.
In Resident Evil, it was shown that when a Passenger who possessed Elizabeth Forbes killed Matt while he was wearing his Gilbert Ring, he went to the Other Side until he could reunite his spirit with his body and revive himself in the living world. Since the Gilbert ring will only resurrect someone who has been killed by a supernatural being, a non-supernatural human who is the host for a Passenger is technically considered a supernatural entity for as long as they are being possessed.
While it was believed that the only way to kill a Passenger was to use the Passenger-killing blade that belonged to Gregor, it was revealed when Tyler died in Promised Land that the death of the host will kill the Passenger if their original bodies were destroyed in order to give them permanent control over their host, as Julian died along with Tyler.
So far in the series, the Passenger spell, or being a Passenger is the first and only form of possession that allows only temporary control of the host. It also the only kind of possession that would show a physical sign(the jet black eyes).
In 500 Years of Solitude, Mia called Elena's cellphone to summon Katherine as a Passenger, right after Katherine performed the spell to transfer herself into Elena's body. This means that the Travelers might be able to sense if one of their members has successfully completed a Passenger spell.
For some reason, Passengers possessing the bodies of vampires or hybrids can only maintain control for a short amount of time, compared to the longer amount of time they can stay in control while possessing a human.
In Promised Land its shown that when the host of a Passenger dies, the Traveler's spirit will return to their dormant original body, as Carl, who was possessing Pam Douglas, informed Pam's husband that he needed something expendable, performing the Purification Spell is fatal to the Passenger's host. Markos also told Damon that it wasn't essential to his plan that his people woke up in their own bodies when Damon threatened to kill them all.
Elena and Tyler are the only non-human hosts seen to have had a Passenger possessing them; Elena was a vampire-doppelgänger who was possessed by Katherine, a witch-doppelgänger, and Tyler was a werewolf-vampire hybrid possessed by the Traveler Julian.