This is the sibling-relationship between the tribrid-doppelgängers, Elena Gilbert, Alexandria Gilbert; and the supernatural hunter, Jeremy Gilbert.
Elena, Alex, and Jeremy were orphans since they lost their parents, Grayson and Miranda Gilbert, in a car crash. Elena and Alex soon discovered they were adopted and that their biological father was Jeremy's uncle, John, making Elena and Alex Jeremy's cousins. They have been shown to genuinely care for each other and Elena and Alex were distraught when Jeremy died, at first in denial, later experiencing a meltdown and Elena had Damon turn off her emotions and Alex delved into black magic to try and bring him back but it ended up backfiring and Alex went dark.
Elena returned to her normal self before being saved from Kol's ghost by Jeremy's. Jeremy realized he couldn't tell Elena and Alex goodbye as it would be too painful. Jeremy is brought back to life by Bonnie so that Elena and Alex won't have to be alone but the cost was her own life. Jeremy is the person Elena and Alex loves most in the world.
They are referred to as "Jeralena" by fans.
Early History[]
Elena and Alex are the biological daughters of Isobel Flemming and John Gilbert. Isobel gave birth to them in New Orleans and Marcel Gerard was able to get them out of town quickly as possible after they were born. The twins were adopted by a family of hunters who loved them no matter what, those hunters being their biological uncle Grayson and aunt Miranda, through their biological father John. Two years later, Miranda gave birth to Jeremy.
After Grayson and Miranda picked Elena and Alex up from a party, their car ran off Wickery Bridge. An unconscious Elena and Alex were saved by Stefan as their parents died. Elena, Alex, and Jeremy were left orphaned and left in the care of their aunt, Jenna. In the aftermath of the crash, Jeremy turned to drugs and a sexual relationship with Vicki as Alex broke up with her boyfriend, Matt.