Hmmm did you read the main kings maker? This version is just the additional smut for the main one.
read the first series! search up the name of this webtoon on here and there should be another and it would show the first season and it would make sense then! this is just the yaoi version of season 2 :)
You should read the original series Kings Maker since this is just a uncensored version of the 2nd season (the first season is them as children and teens) but if you’re okay with a bit of spoilers you’re right. The previous king (wolfgang’s father) used to have children that he used for his pleasure and Shin was one of them (you can read the series to find out why he became one) and through that he met Wolfgang who’s an illegitimate child of the king’s. Together they overthrew the previous King and Shin(the brains behind the operation) set Wolfgang as the new king so bc of that, just as you said, Shin believes Wolfgang only keeps him around as a remembrance of him overthrowing the king.
So the previous king was a pedophile who kept shin as a seggs slave and the new king saved him from it?? Which is why shin doesn’t believe his majesty’s affections for him are real love?