Even though Finn’s story is a trilogy, No Mortal Business book is a stand-alone story. Finn is home, midway through his two weeks off. Every Fae contract has a one day a year off clause as part of being a Fae contract. The two rules to know about dealing with Fae is that everything is negotiable and nothing is free. When Finn didn’t go back to his master at the end of his day off, Paul could easily have hobbled Finn or chained him down so that he could never swim again. Paul owned Finn. Humans have free will. Fae don’t. When they are owned, they are owned completely. The selkie brides of lore marry the fishermen who catch them as a matter of course. When Paul uses Finn, he has every right to. Finn’s body belongs to Paul as much as his service does.
But when Finn realizes that Paul managed to bind Finn to him without Finn actually making a deal with him, it means that the contract was fraudulent. And if the contract is fraudulent, it means that Paul had no right to Finn’s body. And if Paul had no right, it means that the sex he had with the man wasn’t sex, it was rape. Finn realizes that he cannot go back to Paul no matter what it costs. Finn has to come to terms with what has happened to him and he has to deal with what his future holds, free or not, with or without Paul. Giving up his one day of freedom in exchange for the two weeks with Devon is the last bargaining chip he has remaining. He’s dealing with powers far more powerful than the entire Pacific Ocean, and if there’s one thing the legends make clear is mortals who catch the attention of the infinite often suffer more than they win.
I’ll talk more about how much I love Finn’s point of view. He’s part sea lion, and sea lions are both fierce predators and vulnerable prey at the same time. That mix of can I kill it/eat it and will it kill me/eat me drives most of Finn’s thoughts even when he’s in his human shape. Devon believes that Finn is a human who can change into a seal, but that’s not what Finn is. Finn’s selkie. His sea lion (or for simplification, his seal body) is as much his body as his human body is. His tail, which is invisible and non-corporeal in his human shape is still there, and when Devon tweaks it, Finn feels the shiver running up and down his spine.