If Hee Soo really was just trying to help Hye Sung and Do Jin, how come Hye Sung's in a cramped room inside his house? And how come his face goes all dark thunderstorms like a villain's when he looks at Hye Sung? And how can a helpful person call the object of their help a "piece of shit"? How come he still tries to look for Hye Sung as if trying to leave alibis or such? And most important of all, how come Hee Soo doesn't just tell Do Jin he's been keeping Hye Sung all along?
because hee soo is helping hyesung hide, he can't have him roaming around the house. hye sung could also be feeling extremely shitty about himself, and having postpartum. it looks like to me that hee soo has been nagging hyesung all along to get back, and hyesung doesn't like iit when heesoo nags him. heesoo still thinks hyesung is a piece of shit for leaving his baby, and it's heesoo's personality. he tries to look for hyesung so that he doesn't come off suspicious and no one looks for hyesung at his house. he doesn't tell dojin because hyesung does NOT want to be found. heesoo is stuck in the middle between the two, and i think he's genuinely a good person, so i really don't think he's keeping hyesung away from dojin, he's just helping hyesung until he feels comfortable to be found.
let's just read and see what happens, everyone is throwing theories out there, and i think mine adds up so :)!
But i don’t think he has ill intentions. The fact heesoo called him piece of shit tells me he wants him/has been telling him to go back home but he’s simply refusing to. I think heesoo is a good guy, and i don’t think his loyalty is off, he just wants to help someone who has given birth to someone so precious to dojin