Why are you acting like MC wasn’t the one to intentionally string them both along?
He started this whole thing by intentionally using the brother to make the sister jealous so he could get back with her.
He knew she didn’t like him back and had a bf so he went out of his way to manipulate her into obsessing with him because he knew she’s an obsessive POS with an inferiority complex.
Likewise he was stringing the brother along even though the brother was innocent and genuinely liked him. But then he starts acting like the victim at the end. Literally everyone in this manhwa is insane. Haein and the brother are the least crazy but they’re not without their own flaws.

They are crazy, absolutely insane. The possessiveness of the siblings. I know why its called snake bite because both the brother and sister wrapped around bro and stayed on his ass, that he left. I would've been left if that was me. It was fine at first but then they started acting like animals in a rut. MC needs to get up, it took him too long to leave. ANd then it was a lot of relationships going on just for one dude by the way. ┗( T﹏T )┛