Invitation is a weakness of vampires and hybrids, including Original vampires/hybrids. In order to enter any house owned by humans, witches, werewolves, or doppelgängers, vampires or hybrids must be invited by the owners of the home. Once invited, the vampire cannot be uninvited unless the ownership of the house changes.
Series V.S Books
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. The invitation may also come from someone who takes or has taken residence within that dwelling as they are, by extension, also received ownership from the actual owner(s). These barriers are extremely strong, as they are among the few known ways to keep vampires at bay, if killing them 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. Because of this, vampires have been frequently 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, or by otherwise destroying the house.
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.
Ownership can apparently be tampered with, as it is relevant to 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 (presumably) compelling a city official to invoke imminent domain upon the home, giving it heritage status and therefore making the home open to the public without invitation.
It is somewhat unknown what happens to a conscious vampire when they stay in a human's home at the same time that ownership of the house changes. 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 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 awakened became extremely disoriented and was unable to breathe, which made it difficult to properly control his body during his desperate attempts to get out of the house, and he ended up slamming into several walls before he made it outside. It seems unlikely that a fully conscious vampire could be forced into a house where they had not been invited. However, the immortal Silas was able to enter homes of non-vampires without invitation, but this could likely be explained by the fact that while immortals fed on human blood like vampires do, they were not undead and otherwise had no other common similarities. It has also been hinted that Klaus's daughter could possibly be immune to this particular vulnerability of vampires, as she is fully alive rather than undead, and as such, she is capable of owning land/property.
Unlike Its counterpart in TV, vampires can enter homes into which they are invited in by anyone in the house, regardless of whether they live in the house, are the owner, or are 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 said that her bedroom and the living room are part of the original house, so Katherine von Swartzschild, Damon Francesco Salvatore and Stefan Antonio Salvatore cannot enter these rooms, as the original owners are no longer living and are unable to invite them in.
In the TV series, if a vampire is in a house without a human owner, or is invited in by the owner, and then the ownership of the house is changed while the vampire is still in the house, the vampire will become disoriented and will begin to feel as though they are suffocating. This was shown when Elijah was undaggered by Elena after the ownership of the house was transferred to her; he was unable to breathe until he left the house.
- The idea that vampires need to be invited to enter homes or residences has different meanings, but the principle is mostly the same (Protection against undead).
- In some stories, vampires can not enter homes because it is inhabited by living things, and it's like being underwater, murky and full of life.
- In The Vampire Diaries, vampires were not created by Nature compared to the other species. As a defense, Nature weakens the vampires with sunlight, wood, vervain, and other elements (for example, running water weakens vampires in the books). With the purpose to defend against the undead, the living kept the vampires away by banning them entry into their homes. Literally, it's like saying: I invite my own death to my home.
- The origin of inviting a vampire into a home is in the novel Dracula by Bram Stoker. It is mentioned that Dracula was always invited to the homes, causing suspicion about this feature because in those days, people of a high social class invited other people of the same class as a form of education and respect. Because Dracula looked, talked and moved like a person of high social statue, it was easy for him to gain an invitation into others' homes.
- When Bonnie trapped Niklaus in the Gilbert House, it was a reference to the books.
- In the books, Elena's bedroom and living room are part of the original construction of the house, and because of this, and vampires cannot enter these places, as they cannot obtain permission from the original owners.
- Klaus and Hayley's child is the first living hybrid. Therefore, she is able to own property and likely has immunity from invitation.