Wyrmwood by Sam Burns

A dragon searching for a crowning jewel for his fabulous hoard.
A misanthropic incubus who just wants to swim.

Declan might be the world’s only shut-in incubus, but with a father like Elrith, it’s little wonder his faith in people is nonexistant. He skates through life as a computer programmer, closed into his tiny apartment, only feeding by ordering sex workers to his door. But his mother was a water nymph, and occasionally, Declan can’t resist the need to sneak out and swim. This time, he’s in for a surprise.
Augustine is a water dragon who has spent years building the perfect hoard, and now there’s just one thing missing: someone to share it with. When he spots the stunning creature swimming in his pond, he realizes the jewel he sought has come to him. But after centuries of little human contact, he’s out of touch with the meaning of the word consent. When the tempting nymph chafes his control, August can’t figure out how to win him over.
But word of August’s treasure has reached greedy ears, and all he cares for is under threat. Can a dyed-in-the-wool misanthrope teach August the true value of possession before he loses everything?