There might be a jealous rival of Elijah who wants to harm the baby just to get back at him. This rival could be envious of Elijah's newfound connection with the baby and the potential it holds. He would try to create misunderstandings between Elijah and those helping him protect the baby, and also directly attack them when he gets the chance.
One idea could be that Elijah discovers a lost baby and decides to protect it at all costs. He might use his skills and resources to keep the baby safe from various threats in a fantastical world.
Well, it could go either way. They could become closer as they both have a stake in the baby's future. Maybe they start to see each other in a new light, as co - fathers. But there's also a chance that their old rivalries resurface. For example, if there are decisions to be made about the baby's upbringing or training in the supernatural arts. Klaus might want to raise the baby to be more aggressive and powerful, while Elijah might prefer a more diplomatic and refined approach. This could lead to arguments and a strain on their relationship again.
The Originals' enemies, like the werewolves, could be antagonists. They might see the baby as a symbol of the vampires' growth and power and try to harm it. Also, some of the other vampire factions who are against the Mikaelsons could target the baby to get back at Elijah and Katherine.
One common theme is the protection of the baby. Given their supernatural world, there are always threats, and Elena and Elijah have to use their powers and wits to keep the baby safe. For example, in many stories, they face off against other vampires or witches who might want to harm the baby.
The baby could have a really interesting relationship with Klaus. Since Elijah is Klaus's brother, Klaus might be both protective and a bit jealous of the baby. He could see it as a new addition to the family that he needs to look out for, but also as someone who might take away some of the attention from him.
Well, it could have super strength. Since Elijah is a powerful vampire and Elena has her own special traits from being a doppelganger, their baby might inherit enhanced physical abilities. Maybe it could move at super - speed like vampires do, but also have some kind of mental power from Elena's side, like being able to sense danger in a different way than normal vampires.
You can try fanfiction websites like Archive of Our Own (AO3). It has a vast collection of fanfictions, and you're likely to find many Hayley and Elijah baby fanfictions there. Just use the search function and type in the relevant tags.
One great Hayley and Elijah baby fanfiction could be where they face various supernatural threats while protecting their baby. Maybe a story where an old enemy resurfaces and they have to use all their powers and wits to keep their family safe.
Once upon a time, Elijah and the reader met at a grand ball. Their eyes locked across the room and it was like time stood still. Elijah, with his charming smile, walked over to the reader and asked for a dance. From that moment on, their love story began. They spent countless days together, walking in the gardens, sharing their deepest secrets and dreams.