Well, there are several potential plots for this kind of fanfiction. Maybe Natsu is in an environment where he is constantly bullied and abused, like in a guild where some members are jealous of his power. Lucy, who has a kind heart, decides to take him under her wing. She might teach him self - defense or help him build his self - esteem. Another plot could involve Natsu being abused due to a family secret or a prophecy that makes others target him. Lucy, with her intelligence and courage, tries to rewrite the fate that seems to doom Natsu to abuse. This could involve going on quests to find artifacts or information that can change the situation.
I'm not sure specifically which 'natsu is abused lucy fanfiction' is good. You could try searching on popular fanfiction websites like FanFiction.net or Archive of Our Own. There might be some works there that match this theme, but it's important to note that some content might be disturbing depending on how the abuse is depicted.
Another plot could be centered around their fears and hopes. Lucy might be worried about being a good mother, considering her own upbringing. Natsu, on the other hand, could be full of hope that their child will be as strong as him, but also a bit scared that he won't be a good enough father. He then decides to go on a journey to learn from other dads in the guild.
One possible plotline is that Natsu starts writing in the diary about his confusion regarding his feelings for Lucy. He might write about how he gets jealous when other guys show interest in her. Another plot could be that Lucy accidentally discovers the diary and confronts Natsu about it, which then leads to them finally admitting their feelings for each other.
Growth could also be a theme. Nashi would be growing up, learning about her powers (if she has any), and about the world around her. Natsu and Lucy would also be growing as parents, learning how to take care of a child, make decisions for the family, and balance their previous lives with their new roles as parents.
Well, it could be that Lucy has a misunderstanding. Maybe she overhears something that makes her think Natsu is planning to leave the guild without saying goodbye. So, in a fit of panic and anger, she kidnaps him to get an explanation. Then, as the story progresses, they have a heart - to - heart conversation where the misunderstanding is cleared up. It could also be a situation where Lucy is competing with someone else for Natsu's attention, and she thinks that by kidnapping him, she can have him all to herself for a while and figure out how to make him like her more.
One interesting plot could be that they meet in a virtual world while on a quest that is only possible online. They have to team up to defeat a digital monster.
The abuse might also lead to a cycle of revenge or retaliation in the story. The girlfriend could seek to expose Natsu or take actions that would harm his reputation. It could also potentially lead to a path of redemption for Natsu if he realizes his mistakes and tries to make amends.
Perhaps a theme of self - discovery. Through the difficult situation of being abused by his parents, Natsu might start to learn more about himself, his boundaries, and what he truly wants in life. He could realize his own worth despite his parents' actions.
One possible plot could be that Natsu gets hurt during a battle with a powerful dark mage. His friends then have to find a way to heal him while also dealing with the threat of the mage still being around. Maybe they search for a rare magical herb or seek help from a reclusive healer.
One possible theme could be about facing unexpected challenges. Natsu and Lucy would have to deal with the reactions of their friends, family, and schoolmates. Another theme might be growth and maturity as they are forced to grow up quickly due to the pregnancy.