The Originals: Elena, The Original Tribrid

Elena is not the Biological Daughter of Isobel Flemming & John Gilbert, who were the Biological Parents of Ella Gilbert. Elena was actually the Daughter of Leila Astra née Flemming, who was the Older Half-Sister of Isobel and was a Werewitch Hybrid, and Caden Astra, who was a Werewolf of the Crescent Pack. Elena leaves Mystic Falls because Damon, Bonnie, and Ella had done something unforgivable. Bonnie had done a Fertility Spell on her and now she is pregnant... With Elijah's child.