Payment in Kind started out as an excuse to write transactional sex that would hopefully segue into character growth and turned into a hate letter to the concept of true love. And also one of the more ridiculous examples of “fucking while pining” I’ve ever seen.
(Taryn manages to skirt around the pining by accidentally getting Arai and Beale to both independently admit they would like to date her while meddling in their busted-ass relationship. So by the time she manages to fix the mess they’ve made of their own relationship, she’s not at all worried this will result in her getting dumped. She goes straight from “only here for the sex” to “the brains of the entire relationship”.)
Taryn

Taryn is the POV character, and the youngest of the three of them. The story opens the day after she turns nineteen and is about to leave home to defeat the Demon Lord, which no one wants to help her with because it is a suicide mission.
Her father was a famous adventurer who went to slay the Demon Lord when Taryn was very little, and never even made it to the final outpost of society. Taryn and her mother live on the other side of the world from the Demon Lord’s lair, but things have been getting steadily worse and it is noticeable. (It might be less noticeable if it hadn’t resulted in a big hole in their family.)
Taryn basically spent her whole life prepping to be an adventurer and follow in her father’s footsteps. She is an extremely competent and well-rounded adventurer and kind of very bad at being a teenager/young adult. (She was okay at being a kid but when all the other children in town stopped going to school and started up their apprenticeships, she got serious about training.)
She is what she calls “goal-oriented” and those around her would more likely call “stubborn as a mule”. This is how she ends up on a quest most people consider somewhere on the “waste of time” to “suicidal” spectrum, and also how she breaks through Arai and Beale’s busted-ass relationship.
(Taryn's backstory may bear more than a passing resemblance to the protagonist of Dragon Quest 3. Look, it's a classic, okay?)
Arai

Arai is what happens when I’m like “what kind of outgoing man is attractive?” Unsurprisingly, he is doing That Thing I Like where he’s covering up deep-seated insecurities and self-sabotage with Jokes and Hedonism. He is low-key self-harming when he hits on Taryn, TBH.
Arai is an orphan. His mother was a sex worker who had no idea who his father was, but she was tight enough with the other people at the brothel that they continued to take care of Arai when she died young. He still ended up supporting himself rather younger than he might have otherwise.
Luckily, he was born and raised in one of the only cities that’s ever had a functioning Thieves’ Guild, and not only was Arai the kind of street kid who got real good at picking pockets, he is also a consummate salesman. He was a business agent responsible for getting the city’s nobles to buy into the protection racket/competitive obstacle course thing the Thieves’ Guild had going on. He was very good at it, which Beale chalks up to Arai having the same lack of a concept of money as the nobles he was selling bullshit to.
Arai and Beale met when Arai was attempting to convince Beale’s fiancee to have sex with him. Arai just so happened to be ready for a career change at exactly the time Beale was disowned and quietly encouraged to get out of town. Arai’s entire life plan when the story opens is “a: spend as much time with Beale as possible before they find Beale’s true love, then b: suffer nobly for the rest of his life.”
Age-wise, he’s in the middle of Taryn and Beale. He’s also the only one of them who’s ever had anything resembling a steady day job. He is still by far the worst with money because being dirt poor but negotiating with rich-as-fuck nobles all day means he has no idea what anything is actually worth, although also, what does it matter, it’s all fake anyway!
Beale

Beale is the oldest of the main characters. He’s a former noble who hates his family, although he put up with a lot of shady bullshit because, well. Money. If he had tried to break ties with them, they probably wouldn’t have let him. However, he finally managed to do the one thing they legitimately found unforgivable: he fucked up a deal that would have been Good For The Family and then refused to apologize for it.
So Beale was like, what the hell, and picked up the cute Thieves’ Guild rep who had been trying to seduce his fiancee earlier, and accidentally acquired a boyfriend who refuses to actually date him.
Unfortunately for Beale, he finds pig-headedness charming, which was probably also a factor in why he couldn’t stop staring at Taryn as she tried to recruit people to join her Doomed Cause.
Beale is a romantic who spent his whole life bracing for an arranged marriage. He is completely unprepared to deal with the Gordian Knot of his relationship with Arai. When the story opens, Beale is hoping that Arai will get the message if he just continues to stay with Arai long enough. Like at some point his “continuing to not leave” will become real to Arai.
He’s definitely wrong about that! Not pressing the issue is the wrong approach here! Thankfully Arai manages to self-sabotage them both right into Taryn’s life, and Taryn is not in the habit of letting sleeping dogs lie.