>Medieval fantasy

A dragon capture a princess, because he's fed up with human encroaching in his territories.
Turn out the princess is the talking kind, and start negotiating with him, she actually respects him because his alternative was to burn down peasants and farms instead of attacking a well defended princess.
She especially doesn't want to be rescued by a certain dumb-prince because she would then be coerced into a political marriage out of tradition.
So she spills all his weakness and that of the mage likely to accompany him,
After the battle, the dragon, seeing that she told him truths, accepts more of her advice over how to deal with human and even release her.

Start a relationship as she works out what this Dragon want (aside from sleeping on a pile of gold) this one want respect from every creature in his land, plus other quirk like his envy to decorate his lair with a peculiar rock he melt then let cool off.
She starts providing him such things.
Until he unexpectedly asks what she expects of these gifts. She say "nothing", already guessing that his is a prideful and honourable Dragon who don't intend to be treated like a pet.

The story would continue as their exchange become mutually profitable. She gets Dragon-kun to help with affairs, bringing him to negotiation for his imposing presence... getting actual win-win negotiation instead cause "he knows stuff" and have other magical friends. His lair start looking like a castle on its own.

And then there's disruption, like the Dragon's ex-girlfriend who think she'll get his attention back if she dominates all the pesky human around, or the kingdom of the dumb-prince invading hers, Dragon-kun wanting to remain neutral since they also offered him deals.

And so on...
Story would conclude with Dragon-kun revealing he is capable of transforming into a human but it's almost suicidal as he's extremely weak in such form.