You mean when doha went behind him and scared him when he was going to ask him about Siwoon's past? I think it was a scene meant to be a small comic relief panel during a worrying and stressful chapter/arc I don't believe it was meant to foreshadow anything bad about Hamin! Hamin was just thinking freaky things to do with Woojae and then Doha came up behind him and scared tf out of him. I think it was meant to be fun because Hamin is always portrayed as the horny, firm, strong-willed something annoying character but in reality when you know him better you can see he is quite the soft scaredy cat haha also it seems like the story is nearing the end so there shouldn't be any fucked up arc for the other side characters, maybe just a conclusion and happy ending for Taeyoung the guy with family and financial problems that had a crush on Doha
Ah ok just looked like he had a flashback and thought that's why he freaked so much
I'm still wondering why pink hair freaked to much when bottom came up behind him I hope it's not something super fucked up