Erza could also be a main character. Given her strong and motherly side, she would probably take on the role of taking good care of baby Lucy. She might be strict about following a routine for baby Lucy's care. Happy, the flying cat, could be another important character. He could use his unique abilities to search for clues on how to turn Lucy back to normal.
Maybe it could be about a magic spell that accidentally turns Lucy into a baby. Then her friends have to figure out how to reverse the spell while taking care of baby Lucy. They might encounter various challenges and comical situations during this process.
Other dragon slayers could be her potential allies. They might recognize her skills despite her being a princess. Also, magical creatures who are enemies of the dragons, like phoenixes or griffins, could side with her. And some wise old wizards or witches who see her potential might offer their help.
Well, if we consider Lucy as a Dragon Slayer in fanfiction, her magic could be really different from the traditional ones. Maybe she'd have a connection to a celestial dragon, which would be so cool. It would combine her existing celestial spirit magic with the new dragon slayer powers. She could use the stars as a source of power, similar to how other dragon slayers use elements, and it would be a fresh take on her character.
A common theme is self - discovery. Since Lucy is a dragon, she often has to figure out her new powers and what it means to be a dragon. Another theme is acceptance, as she may face prejudice from others who fear or misunderstand her dragon form.
Well, in many such fanfictions, it often involves Natsu and Lucy having a special connection related to dragons. Maybe Natsu's dragon powers play a role in bringing them closer in a romantic or fated - mates - like way. For example, they might go on adventures together where Natsu's dragon instincts protect Lucy in a more profound way than in the original story, and their relationship deepens as they face various challenges side by side.
Another theme could be friendship. In the context of being a dragon slayer, Lucy's relationships with her friends, whether they are also slayers or just her regular comrades, are likely to be explored. Her friends might support her in her new role, or there could be some conflicts related to her new power. Usually, how these relationships evolve is an important part of the fanfiction.
One possible plot could be that Astrid is cursed by an evil sorcerer. At first, she has no idea what's happening to her but slowly starts to notice physical changes like her skin getting scaly. As she turns more and more into a dragon, she has to struggle to maintain her relationships with her friends who are initially afraid of her new form. Eventually, she discovers a way to break the curse through an ancient magic ritual.
One possible plot could be that Eragon, while facing a powerful dark enemy, discovers a hidden ancient magic that causes him to transform into a dragon. As a dragon, he has to quickly adapt to his new form, learning to fly and use his newfound dragon abilities like enhanced strength and fire - breathing. He then uses these powers to defeat the enemy and protect his land.