Vampire Diaries: Why Stefan and Damon Didn't Die When Katherine Did

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In the television adaptation of The Vampire Diaries, the vampires Stefan (Paul Wesley) and Damon Salvatore (Ian Somerhalder) do not die when their sire, Katherine Pierce (Nina Dobrev), is killed. The series establishes the concepts of a sireline, or metaphorical vampire ancestry, as well as a vulnerability where all vampires of a sireline die when the sireline originator is killed. Katherine Pierce loses her vampire status and is later killed, but Damon, Stefan, and the vampires they sired, including Caroline Forbes (Candice King), are unaffected and able to continue their roles in The Vampire Diaries and its spinoffs.

When Finn Mikaelson (Caspar Zafer) is killed in The Vampire Diaries season 3, episode 18, «The Murder of One,» every vampire sired by him or part of the sireline he started died as a result, leading the characters to conclude that the death of a vampire kills all the vampires they sired. However, Katherine becomes human after inadvertently taking the Cure for immortality in The Vampire Diaries season 4 finale, «Graduation.» Her body is killed in The Vampire Diaries season 5, episode 11, «500 Years of Solitude» and her spirit is expelled from the mortal plane in The Vampire Diaries season 5 episode 15, «Gone Girl,» but none of these events harm the vampires she made.

Related: Why Legacies Was Canceled (Where The Vampire Diaries Series Went Wrong)

The explanation for this is that it was later realized that it's an Original vampire who has to die for the sireline to be wiped out, not just any vampire. In The Vampire Diaries universe, a vampire’s sire and the originator of their bloodline, whichever Mikaelson family Original vampire they are descended from, are not always the same person. The death of an