I don’t think so. He was like this before he was kidnapped, he just didn’t have anyone that gave him the attention he needed.
If anything, his parents caused him to be like this.
The Stockholm Syndrome makes the MC go from normal guy to full on Yandere and the kidnapper finds it genuinely very scary when MC shows symptoms of Stockholm syndrome.
So while it definitely is Stockholm syndrome it's unique and puts a twist on the Stockholm syndrome that makes it genuinely satisfying to read if you dislike the usual Stockholm syndrome trope in BL
Nope, he was normal at first, but the abuse his parents put him through made the Stockholm Syndrome turn him Yandere.
He definitely not normal at first. He was pretending to be normal to fit in, all of his relationships were superficial and surface level.
The only real connection he had was with his baby sister.
The abuse from his parents turned him into a masochist (which isn’t that uncommon with abused children).
What turned him into a yandere was the attention he finally got, and the fact that he’d rather be himself than live a fake life.
But he has no experience so he thinks the Ml is the only one that can give him that, when tbh he could go to a bdsm club and find hundreds of guys that can give him the love he wants.
Reread it again from the beginning. It actually shows in lots of detail how he was originally normal (although very depressed) and then slowly develops Stockholm syndrome which first starts with him associating access to food with being obedient.
After he already developed Stockholm syndrome the story shows him associating the abuse he's experiencing currently to the abuse his parents showed him which made the Stockholm spiral out of control while simultaneously cementing the pain = love association his parents tried to gaslight him into.
The reason he went Yandere wasn't because of lack of experience, it was because of Stockholm Syndrome. If it wasn't for the Stockholm Syndrome he'd have gone to seek out a BDSM club or something instead of going after ML even though ML made it unmistakably clear that he doesn't want to have anything to do with MC anymore
is this... stockholm too?