Well, first of all, Elijah would be by Elena's side all the time. He would help her with her daily needs, like getting things she needs or helping her move around when she becomes less mobile during the pregnancy. He would also share his knowledge of the supernatural world with her, so she can better understand what might be happening to her and the baby, and together they can prepare for any challenges that might come their way.
I really like 'Elena and Elijah's Uncharted Journey'. This fanfic takes them on an adventure outside of Mystic Falls. It has a lot of great dialogue that makes their connection seem very real and deep. The author does a wonderful job of building the story around their relationship.
Love is a very common theme. Their relationship, whether it's a budding romance or a deep platonic love, is often explored. Another theme is the idea of sacrifice. Given the complex situations they are often in, one or both may have to sacrifice something for the other.
A fanfiction could explore the idea that Elijah's desire for Elena is part of a bigger prophecy. Maybe there's a hidden message that says if Elijah and Elena are together, it will bring peace to the vampire and human world. So he's driven by this sense of duty as well as his personal feelings for her. This would lead to a lot of internal conflict for Elijah as he tries to balance his feelings with the potential consequences of their relationship.
One idea could be that Elijah tries to court Elena in a very old - fashioned and gentlemanly way. He might take her on trips to historical places he has known over the centuries, sharing his stories and knowledge with her. This would be a contrast to the other vampires' more aggressive approaches towards Elena.
Another theme is loyalty and betrayal. Given their complex relationships and the world they live in, there are often situations where loyalty is tested. For example, Elijah's loyalty to Klaus might be put to the test because of his feelings for Elena. And vice versa, Klaus might feel betrayed if Elijah gets too close to Elena.
In most Elena Elijah Lemon fanfic, Elena is often a central figure, with her own set of goals and emotions. Elijah, on the other hand, has his own backstory and motives that interact with Elena's. The lemon can also be a character in a sense, for example, if it has some kind of sentience or special power that affects the relationship between Elena and Elijah. It might be a source of conflict or a means of bringing them closer.
In an 'elijah and elena pregnant fanfic', Elijah and Elena are the main characters. Elijah might be the one who takes on the role of the provider and protector even more so during Elena's pregnancy. Elena will be dealing with the physical and emotional changes of pregnancy. Their friends and family, though not the main characters, may also be involved, such as Caroline or Klaus who could offer advice or create some sort of conflict in the story related to the pregnancy.
One possible plot could be that Elijah and Elena find out about the pregnancy unexpectedly. They then have to deal with the reactions of their friends and family. There might be some who are happy and supportive, while others are shocked or even against it. They would also need to figure out how to prepare for the baby, like finding a suitable place to live and getting all the necessary baby items.
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.