Elijah and Hayley

This is the relationship between the Original Vampire, Elijah Mikaelson and the hybrid, Hayley Marshall-Kenner.
Elijah and Hayley meet in New Orleans after he discovers that she is being held hostage by witches. Once he is told that she is pregnant with his brother's child, he allows her to move into the Mikaelson Mansion with him, Klaus and later Rebekah. During the first few months of living under the same roof, their friendship grows to be very close and strong. Later on, Hayley tells Klaus that she relied on Elijah because he was nice to her.
They begin to trust and protect each other even more during their fights against witches and vampires and spend more time together despite Elijah's fear of upsetting Klaus and endangering Hayley. Elijah becomes very overprotective when it comes to the safety of Hayley. However on one occasion to save his sister, Elijah had to bite Hayley since the baby's blood was the only solution but did his best not to really hurt her.
When Hayley was about to die because of Mikael, Elijah was very afraid of losing her and decided to open up to her about what he felt for her. After many attempts for them to have their first kiss, Hayley decides to take the first step and kiss him on A Closer Walk With Thee.
Their relationship in the second season began with a distance between them due to Hayley's new status as a hybrid. Elijah tried to help her but she pushed him away because of her belief that Elijah sees her differently than before. Over time she reveals that she hates being a vampire because it has changed her, including the part of her that attracted Elijah, even going so far as to call herself a "monster." Instead of holding onto her humanity Hayley decides to devote herself to eradicating the witches as revenge for them trying to kill Hope. Klaus decided to help her do this after Elijah asked him to do so for Hayley's sake, although it's clear Elijah would rather be the one Hayley relies on moving forward.
After being apart for some time, in Hope's safe house, Hayley decides to tell Elijah about her plans for marriage to Jackson, after talking about her reasons for doing it, Elijah tells her that she has to do the best for Hope's safety, they end up kissing passionately and then make love for the first time on The Map of Moments.
They are referred to as "Haylijah " by the fans.