
Although Narcissistic PD shares features with Histrionic PD, someone with NPD usually relies on self-evaluations and see dependency on others as weak, so it’s unlikely Jaeha as NPD. On the other hand, someone with HPD simply wants the attention of others and would tend to emphasize and exaggerate their positive qualities such as their physical appearance just to become the center of attention. Jaeha shows more of HPD symptoms, from what I've seen.
Also unlikely with stockholm syndrome since it was shown that Sumin already had the tendency to cling onto others even before he met Jaeha. Sumin’s hypersensitivity to abandonment and tendency to cling onto others hint that he may have Borderline PD.
But then again, the story’s actually pretty light and comedic so their characters may just be written in a way that they would match each other’s freaks haha.
((I’m a Psychology graduate btw, so I’m not just talking based on google search haha))

Yea but he didn't care about him for a few chapters, jaeha blackmailed him to get his attention before he started obsessing, thus my assumption about Stockholm syndrom
But indeed you know better than me xD
Maybe you can help me about something? What kind of brain fuckery could make me sleep 23 hours/day?
Two freaks with something wrong with their head that are exact opposites that don’t get along till they click and fit together perfectly, LIKE BRO WERE YOU BORH DROPPED ON YOUR HEAD AS A BABY