Invitation

An Invitation is a magical weakness of Original vampires, vampires, and vampire-hybrids that prevents vampiric beings from entering personally owned homes. In order for a vampiric being to enter any owned house, whether they're humans, witches, werewolves, or doppelgängers, they must first be invited by the owner. Once invited, the vampire cannot be uninvited unless the ownership of the house changes.
==Creation==
When Esther first turned her children into Original vampires, the Spirits turned on them and Nature fought back. Rebekah recounts in Ordinary People that after their transition, neighbors who had opened their homes to them could now keep them out. While Esther was able to find solutions to some of the consequences, this has remained absolute and neither Rebekah nor Esther offered any more information.
In Never Let Me Go, however, Bonnie explains to Matt that the reason vampires are unable to cross the threshold of owned property by the living was due to magic, a threshold spell. This spell is absolute with no known magical loophole and the only way to reseal a house is to sign over the deed of the property to someone else. Seemingly contradictory to this, in Where Nothing Stays Buried, Van explains to Lucien that it wasn't magic keeping him out of the Mikaelson home. Since they signed over the deed to the place to Freya, he couldn't get in unless she invited him.
The events surrounding around the invitation's creation, beyond the direct consequence of the creation of vampires, has not been made clear. Whether or not the invitation to bypass thresholds is exclusively a "spell" decreed by the Spirits or a "supernatural law" set forth by Nature remains unknown.
==History==
This protection appears to manifest itself as an invisible barrier that automatically erects itself on the door lintels and any available entrance in a human home if a vampire tries to enter that dwelling without an invitation from the owner. An invitation into a home may also come from someone who is either currently residing in the house or who has in the past, as they are, by extension, also receiving ownership from the actual owner(s). This extended ownership even continues long after a person who has lived in the house for a significant amount leaves, and an invitation into a home can be extended even over the phone from thousands of miles away. This was demonstrated by Jo Laughlin, who invited Stefan Salvatore into the Parker House despite the fact that she hadn't been there in almost twenty years, and that she was in Mystic Falls, Virginia while he was 3,000 miles away in Portland, Oregon.
These invitation barriers are extremely strong, as they are among the few known ways to keep vampires at bay, if killing the owner is not an option. The barrier only holds for as long as the vampire remains uninvited, the owner(s) remain alive, and the dwelling remains standing. If the vampire is invited in, the barrier magically disappears, and if the owner dies or is killed, the house will no longer have an invitation barrier so long as the house's ownership doesn't revert to another person, such as if it's left to a family member in a will. If a homeowner dies and is then resurrected, the magical invitation barrier is "deactivated" despite the owner returning to life, and it is unknown if the ownership can be refreshed in the case that this should happen.
Vampires who are unable to convince a human to invite them into their home have often been known to resort to other methods to enter the house, such as setting the house on fire to either destroy the home or to drive the humans inside out of the house and the protection it provides. Other methods of destruction will often yield the same effect, such as when Klaus started throwing fence pikes through the Gilbert House when he wasn't immediately extended an invitation.
Vampires have been known to use this weakness to their advantage by establishing a home with a human owner so as to keep other unfriendly vampires from gaining access to their homes without invitation. Some vampires even go so far as to compel their human title-holders not to give a specific vampire entry, such as when Frederick compelled Miss Gibbons not to allow Damon to enter her home, where Stefan was being held captive and tortured.
Ownership can apparently be tampered with, as the magical protection is based on signed legal documents. This was seen when the Salvatores opted to bestow ownership the Salvatore Boarding House to Elena so she could use it as a safe house after Klaus came to Mystic Falls. Elijah was able to bypass the protection of the Guerrera Mansion in a similar manner by having a city official to invoke upon the home, giving it heritage status and therefore making the home open to the public without invitation.
If the ownership of a home changes while a vampire is still inside, there can be very violent side effects. For example, in The Dinner Party, Elijah was daggered and brought into the Salvatore Boarding House while the house was still in the name of the deceased Zach Salvatore and could be entered by any vampire without invitation. However, while Elijah was kept daggered and unconscious in the basement cellar of the house, the Salvatore brothers had a lawyer transfer ownership to Elena in order to use it as a "safe house" from any vampires who try to hurt or abduct her for Klaus. When Elena undaggered Elijah some days later, Elijah immediately became disoriented upon reawakening and was unable to breathe, which made it difficult to properly control his body during his desperate attempts to get out of the house, causing him to accidentally slamming into several walls in his frantic attempt to leave the house. It seems unlikely that a fully conscious vampire could be forced into a house where they had not been invited. 
A vampire who is conscious and in the home of a human when the ownership changes, the vampire will be violently ejected from the house by a magical force. This was demonstrated in Never Let Me Go, when Lily Salvatore transferred the deed to the Salvatore Boarding House to her housekeeper Lucy to prevent the Mystic Falls Gang from rescuing Caroline. Stefan and Caroline were both still inside the boarding house at the time, and the former was forcibly yanked backward out the doors to the balcony and into the backyard below, while Caroline was pulled out into the hall and down the stairs by an invisible force until the housekeeper finally invited Caroline in, stopping the ejection process.
==Throughout the Novels==
Unlike its TV counterpart, vampires can enter homes into which they are invited in by anyone in the house at the time, whether they're the owner, a resident, or a guest. However, if a house contains old structures of the original house along with renovated portions of the house that were added much later, the vampire must be invited into those parts of the house by only the original owners; for example, Elena Gilbert said that her bedroom and the living room are part of the original house, so Katherine, Damon and Stefan cannot enter these rooms, as the original owners are no longer living and are unable to invite them in.
==Revoked Invitation==
In Klaus, it is shown that while a vampire who has been invited into a house cannot technically have their invitation revoked, there is a loophole to this rule—if the ownership of a house changes, then the vampire will have to be re-invited by the new owner. If a vampire is desiccated or unconscious when the ownership changes, such as in the case of the daggered Elijah, the vampire will become disoriented and will begin to feel as though they are suffocating until they are able to flee from the house. It is possible that Elijah had also been pulled out by the same effect that tore Stefan from a house in later seasons, which could have made it the reason why Elijah had trouble leaving and seemed disoriented.
In Never Let Me Go, it is shown that vampires in a house that changes ownership will be pulled by an invisible force until they are out of the house, and they will need to be re-invited to gain entry. This was demonstrated when the ownership of the boarding house changed while Stefan and Caroline were still inside, causing Stefan to be pulled backward and out the glass doors into the yard while Caroline was pulled downstairs toward the front door. This could have been the same effect that caused Elijah to flee in a disoriented manner by running into walls when he was forced to leave the Salvatore house in the episode Klaus.
==Known Loopholes==
There are only a few known, non-magical, loopholes to the invitation barrier against vampires. There is currently no known way for such a barrier to be broken with magic.
*One of the quickest and easiest ways to break the barrier for a vampire to enter owned property is to kill said owner of the property.
*Humans can be compelled by vampires for them to be let into owned property.
*The deed to the property can be made null through legal manipulations.
*Eminent domain can be cast to make the property available to the public.
==Trivia==
*Prior to becoming a fully activated tribrid, Hope Mikaelson was a hybrid with vampire blood, able to own property and immune towards invitations. After dying and completing her transition, she now requires invitations to enter owned property, such as Trudy's house.
*Similar to the natural weakness of vampires, Lucien had, presumably, Alexis cast an unusual boundary spell over his penthouse, as shown in You Hung the Moon. The spell prevented vampires, such as Elijah, from other sirelines beyond his own to be unable to enter without an invitation. Other supernatural species, such as werewolves, could pass through the boundary unobstructed. Aurora attempted to force Cami through the threshold, however the spell actively repelled her, causing Cami excruciating pain that caused her to bleed from the eyes and nose. Hayley, however, was unaffected by the spell. This was due to her being an "unsired" vampire, regardless of being a werewolf-vampire hybrid, and the spell's limitation of preventing vampires from specific sirelines to enter.
*Despite being a private school for supernatural children, the Salvatore Boarding School is seemingly still protected by the invitation, as Malachai still had to have someone "invite" him on to the property. Kai compelled Dorian to "go find someone who would be able to invite [him] in." Who Dorian had invite him in remains unknown.
==See also==
Category:Weaknesses
Category:Original Vampires
Category:Vampires
Category:Hybrids