
Seriously, all bad things are traced to him. Leaving his son on Earth, not ever interfering or even visiting. Only getting involved after the mom dies, but before the son can finish his revenge, which results in the son seeking revenge later and being punished for it. Son becomes a playboy because he can't find his mom, which his dad definitely prevented. He only falls in love with a human because he was sent to Earth by terrible dad, and for what? Cause he almost got intimate with some princess? It's not like you ever put your foot down on his degenerate ways before, so isn't this also your fault daddy-oh? Inserting himself unnecessarily into his son's relationship, to the point of trying to force a marriage. Let's say he had succeded on that. Did he think it would have good results? Wouldn't it have just been a terrible marriage for both parties? It's not like Shinhu was gonna be loyal and treat her nice, he doesn't love her, and she even got in the way of his actual love. What is this father thinking? Really up there on my awful dad tier list.
Also, I wish we could have gotten some answer on what happened to Shinhu's mom.

If I were to have listened to the comments, I would have skipped this. I'm glad I didn't since I'm enjoying it. Honestly, like night and day, the comments don't match what I'm reading at all... it IS probably like a soap opera though. Probably the only somewhat accurate comment I saw... not that I would know. I don't watch soap operas.

The ML is a huge red flag. I thoroughly enjoyed his twisted nature (though him being sweet at the end was also great). Favorite line is when he says, "I wanna pierce your neck, too." I already thought this guy looked like a vampire, lol. In another reality, this is a vampire yaoi. I'd so eat that up. A vampire BL with this sort of setting.

I don't like the ending, and yes I do have an alternative ending in mind. I was actually typing it, but accidentally navigated away. I don't feel like retyping all of that, so instead of getting all the detail plus the sides I wrote, you get a TL/DR (sorry).
Zin successfully sends Idris away from the palace unnoticed, Zin reports back everyone is dead, Zin and Idris have reunion at Bellet Mansion, blah blah, embrace as sun rises, roll credits on main story.
Side summaries. Side1: Idris is recovering, Zin seeks disguise for Idris, princess wants to talk about coronation/marriage. Side2: Princess and Zin get married, Zin escapes after wedding and returns to longer haired BLONDE Idris (the invention of hair dye), Zin makes Idris the new head of the Bellet guards and gives Idris a new name. Side3: Empress (formerly princess) sends people to bring Zin who has been avoiding her, they finally have the heir talk. Zin balks, Idris reassures. Empress and Zin arrange baby making schedule. Side4: Empress and Zin's baby is born with blonde hair and purple eyes, they name him Klyne. Stuff with Idris, such as talking about baby, physical intimacy with eachother, yada yada. Side5: Couple years pass, Zin is reading letter from disabled former Idris squire, the guy used the money Zin was sending him to study and has opened an apothecary where his sister sells the medicine he makes. Butler comes in, reports Zin's brother has had a baby with his wife, Zin orders to prepare congratulatory letter/gift and also notes that the marquisdom should probably be left to his brother's children as his son shall be inheriting the kingdom. Zin prepares for day out with son plus Idris. Story should end with happy family feels (also, Idris smiles). The End.

Baby making can only mean having a baby together, I think that's obvious. Also, this story has a medieval type setting, so it's unlikely to be artificial insemination, and I'm not the type to shy away from uncomfortable things. That being said, I never planned to go over the how they make the baby or show anything, so you could headcannon anything you like for how they made it.
Anywho, I like GOOD endings. Good doesn't equal perfectly happy. The author actually introduced a plot hole just for their have a cake and eat it too ending. The only other good ending that could exist for this story is an outright tragic one, and I don't like tragedies.

I mean the medieval method that’s equivalent to that (eg. Injecting sperm with a syringe, still not possible yeah). I just can’t accept they’ll have a baby together by physical connection or not. whether that scene will be shown or not. Plus, I’m an Antinatalism so I don’t want them to have a child only for the convenience, instead of love. Idris won’t properly be presented and fulfil the role of a father either. for me, I would prefer having them adopt an orphan kid that looks similar to both of them and try to conceal his background.
So, if I were to guess what's going on in this yaoi, the "gym" is actually a training facility for male prostitutes. The black collared ones are general sale, but the red collared ones are private property. It's safe to say our protag is gonna be a red collar in the future.
Honestly, what's really cool here is the "gym" can really fly under the radar. All members are "willing" as they seem to have been rewired to see sex as ordinary exercise. They still continue their normal lives, so no one just suspiciously disappears. If there's a such thing as retirement, they can reset their minds and direct them to an actual gym. Of course, the affects on the body will remain, but that's for the individual to figure out.
congrats you added more depth to the story than the author probably even thought of adding