The Cure was introduced during Season 4 of The Vampire Diaries becoming a key point in the story and four vampires used this remedy to regain their humanity!
In the 1st century BC, in The Vampire Diaries , Bonnie Bennett's ancestor, Qetsiyah fell in love with another wizard named Silas. It was she who created a spell to make them immortal but after Silas' betrayal, she also created a cure (The Cure) in order to undo his spell. Instead of taking it, Silas chose to remain buried in a cave on a remote island for 2,000 years. During season 4 of The Vampire Diaries, Atticus Shane convinced Elena and her friends to help him raise Silas from the dead in exchange for The Cure. It was only after arriving on the island that they learned that there was only one dose. The Cure changed hands throughout the second half of the season. Finally, four vampires were able to take or taste this remedy to find their humanity in The Vampire Diaries!