*The following text may contain spoilers.
Elijah Mikaelson is an Original Vampire, son of Mikael and Esther. He has 6 siblings: a deceased unnamed older brother, 3 younger brothers named Finn, Kol and Henrik, one younger sister named Rebekah and a younger half-brother – Niklaus.
Elijah was born in Mystic Falls approx 1000 years ago. During their human years he was closest to his siblings Niklaus and Rebekah.
They lived among werewolves for about 20 years. He enjoyed sword fighting with Nikalus much to the dismay of their father Mikael who viewed Klaus as most reckless. Elijah and Nikalus both fell in love with the same woman - Tatia, although she had a child by another man. According to Elijah she was exquisite beauty. Both brothers fought over her until they realized family was more important.
One morning, Niklaus took their youngest brother Henrik to watch the men turn into beasts but things went out of hand and Henrik was killed by a werewolf. The entire family was devastated by this and to protect their children, Mikael came up with a ritual, performed by Esther, which made them vampires and immortal. He along with Esther sacrificed Tatia, laced some wine with her blood then stabbed Elijah along with his siblings in the heart and made them drink the wine.
After becoming a vampire Elijah along with his family burnt down the white oak tree in their village, used for the ritual, as it was the only thing that could kill them. Some witches saved the ash from the tree so it could be used with a silver dagger to neutralize all of the originals except Niklaus who also had a werewolf gene. After their mother Esther was killed by Niklaus who framed Mikale and lied to the rest of his siblings, Elijah, Rebekah and Niklaus promised that they will never turn their back on each other and that they will always stick together as one. Always and forever.
Wise, Elijah is shown to be the most loyal and moral, generally gentle, calm and even tempered unless you cross him. Elijah is seen to show more compassion and empathy for humans. However if crossed, Elijah will have no problem with killing but he feels guilt and remorse afterwards. He is also cunning and manipulative in order to get his way. He lives by the code of ethics, values and morals and is considered to be a man of words. He considers family above all and feels pain if any of his family members is in danger and would go to extreme lengths to protect his siblings from any harm.
Always moral and noble among his siblings, Elijah was helping his brother Niklaus to break his curse in late 14th century. He met Katerina, a Petrova doppleganger who Klaus was about to sacrifice to break his curse and tried to persuade him to spare her life. However things did not go as planned and Katerina fled before the ritual. Klaus assumed Elijah helped her. Elijah promised his brother he will find her and Klaus responded with a promise of his own, if he did not find Katerina he would be killed.
After finding out that Niklaus had daggered his remaining siblings, he plotted with the Salvatores to find a way to kill Klaus to avenge them. But coming to know that Klaus had never thrown their bodies into the sea, Elijah spared his life and asked him to take him to where his siblings were. Klaus betrayed him again by daggering him and “reuniting” him with his family.
After Damon resurrected Elijah he began to fight Klaus. And when he learned the truth about what really happened to their mother, he resurrected his daggered brothers Kol and Finn and his sister Rebekah and together they told Klaus they were leaving him alone forever. However Esther returned from the dead and plotted to kill all her children. This left Elijah to take matters in his own hands and protect his siblings from their mother. Together with Klaus, Kol and Rebekah they managed to temporary stop Esther from carrying out her plans. Elijah was greatly affected by Esther’s words to him and he left Mystic Falls.
Up until now, Elijah has been neutralized with a dagger and then resurrected 5 times. He is the character who has died most times in the show.