Basilisk by Rinda Elliott

As a basilisk, Bain Ophion has lived over two hundred years. For the last ten, he’s worked for his best friend, a sorcerer who runs Protective Solutions. Bain loves his work as a bodyguard and especially loves proving his skills when clients take one look at him and doubt. Yeah, he may dress flashy and have androgynous looks, but he also comes with preternatural strength. Humans don’t know that, though. Because, like all his fellow bodyguards, he uses a glamour to hide what doesn’t blend. Most humans aren’t ready to know about the supernatural world around them, but he’s about to learn that there are a few who are special.
Clive Manning has no idea which of his new clients is threatening his life, but when they send someone to break into his home, he knows he can’t handle this alone. He lives a perfectly ordered life and works from home for a reason. Lifelong fear. He calls Protective Solutions and hires a bodyguard, and when that man shows up, Clive is shocked. He expected something like a man in black and instead, he got a rockstar.
But Clive is highly attracted to this colorful bodyguard and soon Bain proves he’s very good at his job…among other things.

Basilisk is a long novella with a sexy shapeshifter who’s stunned by his fierce attraction to an uptight accountant and the accountant who learns his lifetime of fear had good reason.