One idea could be that the dragon is actually a cursed prince. The princess discovers this and tries to break the curse. Their love blossoms as they face various challenges together in the process of finding a cure.
The princess could be a magic - user herself. She gets lost in the dragon's lair while exploring magic. The dragon is initially hostile but then realizes she is different. They start to communicate through magic, and gradually, love develops. They have to overcome the fear of the outside world that would not accept their relationship.
Maybe the dragon saves the princess from a rival kingdom. At first, the princess is afraid, but as the dragon protects her and they spend time together, she sees his gentle side and they fall in love. They then have to figure out how to be together despite the differences between their species and the opinions of the people around them.
One idea could be the princess having to deal with a political crisis in her kingdom. Maybe she has to negotiate with a neighboring kingdom to avoid war while also facing opposition from within her own court.
One idea could be exploring the backstory of the dragon commanders. Maybe how they were chosen and trained before they took on their important roles. Another could be a story where a dragon commander has to form an alliance with an unexpected group to save their land from a new, powerful threat.
One idea could be a dragon who is injured and is found by a human. The human nurses the dragon back to health and they form an unbreakable bond. Then they go on adventures together, facing various challenges in a magical world.
One idea could be exploring an alternate universe where the main characters have different powers related to dragons. For example, the protagonist could have the ability to communicate telepathically with all dragons instead of just a specific one.
Well, a possible plot for a Dragon Symmetra fanfic could involve her being an outcast in her dragon society because of her unique symmetra powers. She then meets a human who doesn't fear her but is instead intrigued. Together, they explore the secrets of her powers and how they can be used for good. Or perhaps she is sent on a quest by the dragon elders to retrieve a stolen relic, and along the way, she discovers a whole new side to her dragon heritage that she never knew existed.
One idea could be that the last dragon is discovered by a young adventurer. They form an unlikely bond and together they set out to find a way to save the dragon's kind from extinction. Maybe there are ancient prophecies or hidden magic involved.
One idea could be that Dragon discovers Luffy's true potential during a battle against a common enemy. Maybe Dragon secretly aids Luffy without him knowing, guiding the wind or weather to give Luffy an advantage. This would add an interesting layer of mystery to their relationship within the fanfic.
Maybe in the 'dragon knot fanfic', there is a hidden society that protects the dragon knots. A protagonist stumbles upon this society and has to prove themselves worthy to learn about the secrets of the dragon knots and their connection to the dragons.
A plot idea might involve Baby Princess Luna having a dream where she travels to the future and sees herself as a great queen. She then wakes up determined to start learning all the things she'll need to know. So she tries to follow around the older princesses and imitate their lessons, but she often misunderstands and does things in her own unique, cute way. For example, she thinks that 'diplomacy' means sharing her toys with everyone in the kingdom.
One idea could be a mystery plot. The princess notices strange things happening in the palace, like items going missing or strange noises at night. The butlers team up with her to solve the mystery. Another idea is a competition plot. There could be a butler competition where they have to show off their skills, and the princess is the judge. It could lead to some fun and flirty interactions.