The relationship between the tribrid-doppelgänger, Alexandria Gilbert and the witch, Bonnie Bennett.
They have known each other since birth and became close friends. They are both best friends with Caroline and Elena. Bonnie turned her back on Alex after her grandmother died, blaming Damon and Stefan and not wanting Alex to choose between her and them. She later forgave her when she saw her crying. Alex supported Bonnie dating her brother, Jeremy. Their relationship turned sour when Alex turned dark in Season Four and turned on Bonnie. Alex tried to kill her and their friends. When Alex turned good, Bonnie immediately forgave her, saying she knew what it's like to not be yourself. Alex and Bonnie continued to be close throughout the next few seasons.