Another option could be an OC dark mage who had a change of heart. He could have met Lucy's mother during one of his less - evil moments. Their relationship might have been a secret because of his reputation. In the fanfic, his identity as Lucy's father could be revealed gradually, like through some hidden artifacts or old spells that start to show the truth as Lucy grows stronger in her magic abilities.
It could be an OC nobleman. In the fanfic, perhaps he met Lucy's mother at a grand ball. He might have had a brief but passionate relationship with her. However, he was forced to abandon her due to family or political pressures. This would add a lot of drama to the fanfic, especially if Lucy discovers her true heritage later on and has to face the consequences of her father's actions.
A great storyline could be that her real father is an OC time - traveling mage. He accidentally travels to the future and falls in love with Lucy's mother. But then he gets trapped in the future and has to watch his daughter grow up from afar. This could lead to some really emotional scenes when they finally meet.
Death the Kid would be an extremely interesting character for Lucy to interact with. His obsession with symmetry and his powerful abilities as a meister could lead to some really unique scenarios. Lucy might be both fascinated and a bit put off by his quirks at first. But as they get to know each other, they could learn a great deal from one another. For example, Death the Kid could help Lucy understand the importance of precision in combat, which could enhance her use of celestial spirit magic, while Lucy could introduce him to the concept of celestial spirits and their different powers.
First, focus on Lucy's emotions. Since she's pregnant, she'll have a whole range of feelings like joy, fear, and anticipation. Show how these emotions influence her actions and decisions. For example, she might be more cautious about going on missions. Second, develop the relationships around her. How do her friends and family react? Their reactions can also drive the story. Third, give her a goal related to the pregnancy, like ensuring a safe future for her child, and let her character grow as she tries to achieve that goal.
Lucy might gain more confidence. Knowing that her father loves her and is there for her could make her feel more secure. This could translate into her being more assertive in her adventures and less likely to be pushed around by others.
Another theme is the exploration of magic. Lucy has her celestial magic, and the OC usually has some form of unique magic as well. The fanfictions often explore how their different magics can work together or clash. It's interesting to see how the authors play with the magic system in the Fairy Tail universe to create new and exciting storylines for Lucy and the OC.
Well, obviously she'll interact with her past self. It would be really interesting to see how she reacts to seeing a younger and more naive version of herself. She could also meet characters who are no longer alive in the present. For example, if there were any great wizards from the past who played important roles in the history of magic. Additionally, she might cross paths with some of the villains from the past who were causing trouble long before the current villains in the story. This could change her perspective on the whole conflict in the present.
Gray could also be a possibility. He and Lucy have a friendly rivalry and there are moments where their relationship could be interpreted as having deeper feelings. It would be an interesting twist if Gray was the father, as it would change the dynamics between him, Natsu, and Lucy in the fanfic.
Yes, there are quite a few out there. You can start by looking on popular fanfic websites like Archive of Our Own. Just search for 'luffy x lucy heartfilia' and you'll find a variety of stories with different plotlines and writing styles.
Another fanfic could focus on Lucy's relationship with Erza. Maybe they team up for a tournament within the Fairy Tail guild. Along the way, they face tough opponents and have to rely on each other's strengths. Lucy's strategic thinking combined with Erza's powerful combat skills would make for an exciting story.
You can start by looking on fanfiction.net. It has a large collection of Fairy Tail fanfictions, including those with an OC and Lucy Heartfilia. Just use the search function and type in relevant keywords.