It could be about Lucy having an adventure in the world where celestial dragons exist. Maybe she befriends one or tries to change their cruel ways.
Well, it could start with Lucy being in a situation where she witnesses the destruction caused by a celestial dragon. This event stirs something deep within her, and she decides she wants to be able to protect everyone from such a threat. So, she embarks on a journey to become a celestial dragon slayer. She may travel to different realms or seek out rare magical items that can enhance her abilities. As she progresses, she could form alliances with other powerful mages who share her goal or have knowledge about celestial dragons. And gradually, she builds her skills and reputation as a celestial dragon slayer.
It could be another powerful celestial dragon who opposes Lucy's ideas or presence.
One interesting aspect could be how she trains to become a Celestial Dragon Slayer. Maybe she discovers an ancient magic that combines the two, and she has to learn to control the newfound power. This could lead to some great character development as she struggles with the increased power and the responsibility that comes with it.
The plot could be about Lucy taking care of the baby dragon. Maybe she has to hide it from others who might want to harm it. She could be on a quest to find a safe place for the dragon to grow up.
Well, one possible plot could be that Luffy starts off as a Celestial Dragon but then has a change of heart due to seeing the cruelty and inequality in the world. He might use his privileged position to start making changes from within the Celestial Dragon system.
Well, it could be about Natsu having some sort of special connection to the celestial dragons. Maybe he discovers he has celestial dragon blood in him and has to deal with the powers and responsibilities that come with it. He might also encounter other characters who either fear or revere him because of this newfound aspect of his identity.
Well, a plot could revolve around Lucy being the only one who can stop an ancient Celestial Dragon that has been awakened from its slumber and is causing chaos. As a Celestial Dragon Slayer, she has to figure out how to communicate with the dragon first and then find a way to either calm it or defeat it. This could lead to her delving deeper into the lore of Celestial Dragons and her own family's connection to them.
Perhaps an ancient sorcerer who has the ability to control celestial dragons. He sees Lucy as an obstacle to his domination over the world using the power of these dragons. He would use his vast knowledge of magic and his control over the dragons to try and defeat her.
She could have the ability to breathe celestial - themed 'dragon breath'. For instance, it might be a blast of star - like energy that can pierce through dark magic. Her celestial spirits might also gain new forms or abilities. For example, Aquarius could become a more combat - ready mermaid with dragon - like fins that can slice through water and enemies.
In these fanfictions, a major theme is the combination of different magics. Lucy has her celestial spirit magic and now as a dragon slayer, how these two magics interact and complement each other. Another theme is the search for identity. She is no longer just Lucy the celestial wizard but also a dragon slayer, and she has to figure out what that means for her place in the world and among her friends.