Underdog by Michaela Haze

Luiz Ramirez was created by the Devil, stitched together from damned souls to become a Hellhound.
Having escaped Lucifer by the skin of his teeth, his only option was to seek sanctuary and become a soul broker, giving people their dreams… One contract at a time.
When a dead hound is left outside of his office, all signs point to Vincent Rose, his ex-boyfriend, and the local human herder.
Luiz is determined to solve the murder and find out who is responsible.
But a very human police officer has his eye on Luiz, and there is only one rule when it comes to Demons.
Humans can never know.