Ok, random book idea cuz ADHD brain is going brrrr
Basically, a role-reversal on the basic "dragon kidnaps princess" story. Like she keeps the poor beast chained up in the dungeon.
I'm thinking the dragon was peaceful to begin with, and lived far away. But the princess took advantage of that and kidnapped the dragon, bringing it back to their kingdom and spouting something about how she stopped the dragon who was about to rampage through it. She's then crowned the new ruler because of how good of a deed it was, leaving the dragon in the depths of the castle, being fed only scraps to keep it barely alive, and used essentially as a rancor pit.