In season four, Elena must decide whether to die or to feed on human blood so she can fully transition into a vampire.
After realizing Stefan's desperation to keep her alive, Elena completes her transition.
She is the biological daughter of John Gilbert and Isobel Flemming, and adopted daughter of Grayson and Miranda Gilbert.
She has a younger adoptive brother named Jeremy Gilbert, who is later revealed to be her biological cousin.
Elena Gilbert (based on Elena Gilbert from the novels) is the central character and the female lead of the series for the first six seasons.
The sacrifice later takes place, but Elena is saved because John sacrificed himself for her after Bonnie magically enchants him.
However, her Aunt Jenna is turned into a vampire and, as part of the sacrifice, is killed by Klaus, leaving Elena without a guardian.
Kevin Williamson and Julie Plec adapted the TV series from L. The series is set in the fictional town of Mystic Falls, Virginia.
Some of the characters appeared in the spin-off series, The Originals.