Spin off that's better than the main story, novel spoilers

Volume 1: MC is a hyper dominant omega bodyguard who accidentally rolled in the sheets with ML hyper dominant alpha some years ago while on a mission and was marked. He's been living as a single dad while working with his team at a small security firm since then but is forced to take a contract working as ML's bodyguard because he's strapped for cash due to his mother's medical emergency. Some heretic organization is trying to kidnap hyper dominant alphas and sell off their sperm.

The team has to abide by all these random absurd rules that ML has including not getting within 5m radius of him, not speaking to him, not disturbing him with their presence, etc etc. Everyone gripes because ML has a super shitty personality and will quite literally shoot anyone who annoys him with his favorite .50 cal Desert Eagle. MC almost gets shot and drowned and eventually gets in a fist fight with ML. Doesn't stop him from openly admiring ML's face, which ML acknowledges. ML's brother Grayson (long blonde haired friend of ML from Kiss Me Liar) visits and exposes ML's fear of dogs.

Despite being a recluse, ML is forced to have social interactions and attend a party for Keith Pittman (ML of Kiss Me Liar) where MC first meets Yeonwoo.

Volume 2: ML is exposed to omega pheromones and MC gives him a handjob in the garden. It's revealed that ML struggles with insomnia and frequently takes more than the recommended dose of inhibitors and sleeping meds. During a routine visit to the hospital, the team is attacked and MC and ML become stranded in the wilderness where MC is injured by a pack of coyotes.

MC is temporarily hospitalized for animal bites and returns to his job only to find ML swimming naked in the ocean. They have sex on the beach.

Volume 3: The couple engage in a clandestine affair while ML struggles with his feelings. He believes that MC is having an affair with him while in a relationship because he saw MC and his sister Emma together. ML fears that his pheromones will turn MC into an omega as he believes MC is a beta. He becomes increasingly confused when he sees MC's c-section scar and learns that MC has a child with an unknown partner. He overhears MC turning down one of his coworkers by saying he only wishes to be with his child's other parent (whom he assumes is a woman).

MC learns that ML has suicidal tendencies and is afraid of dogs because he had never shared his rut with anyone until he marked MC some years ago. However, ML forgot about their encounter and was tricked into believing he committed beastiality by his sociopathic brother Grayson. MC reveals his omega identity and introduces ML to their son. MC proposes to ML.

The couple have two sons Pete and Cecil as well as an unnamed daughter.

There's another volume of side stories, but I haven't read it yet.