A young mage could be a main character. They are intrigued by the dragon's breath and study it, hoping to use it to enhance their magic.
A fearless knight could also be a main character. They are tasked with slaying the dragon but instead find themselves in awe of the dragon's breath and start to question their mission. They might end up trying to protect the dragon instead.
Naruto is surely a main character. In addition, Sasuke could also be an important figure in this fanfiction. Maybe he has a different relationship with Naruto in the context of the Breath of the Sun. He could be either a rival in trying to obtain these new powers or an ally in protecting the world from the potential threats that come with the Breath of the Sun. And don't forget about Kakashi. He might play a role in guiding Naruto and the others in this new adventure.
One idea could be a story where the dragon's breath has a unique power, like the ability to heal. A young hero discovers this and tries to use it to save a dying land.
The dragons themselves are likely to be main characters. There could be an alpha dragon that leads the revenge, with its own distinct personality and abilities.
Well, of course, the twin dragons themselves are likely to be the main characters. They might have names like Zephyr and Nova. Zephyr could be the more impulsive one, always ready to take action, while Nova is the more cautious and thoughtful twin.
Obviously, the prince of dragons is one of the main characters. He's likely to be the central figure around which the story revolves.
Maybe there is a young wizard in training. The dragon's pet crosses his path and they form an unlikely bond. The wizard uses his growing magic skills to protect the pet from those who would harm it for its unique abilities.
It's hard to say without actually reading it. It could be the dragons themselves, perhaps a heroic dragon who leads the others at this daybreak. Or it might be dragon riders if they are part of the story.
Maybe there's a human character, like a young wizard named Alex. Alex could have a special bond with the dragons and be involved in their affairs, using magic to communicate and assist them.
It's hard to say for sure without reading it all, but likely the dragons themselves would be main characters. Maybe there's a heroic dragon that stands out.
The dragon itself is surely a main character. There could also be a wizard or sorcerer who plays a crucial role in the dragon's rebirth or its journey after rebirth.