Um he saw him in a photo with the other guy that he didn't like. So he thought he was betrayed again. No there is no misunderstanding with 'Zach'. He dislikes Zach because he made him feel pathetic in front of MinJi. He doesn't care whether it was intentional or not. T.
he's not attacking them because he dislikes his childhood friend, it's a misunderstanding that started with the fake phone number/bank account thing that I'm pretty sure if I remember correctly was Jiho's fault for being swindled but still continuing to mess up (I might be wrong on this part it's been a while). Then burn knuckle, Hyung suk (Daniel) and his friends bit the swindlers ass who turned out to be the previous gang leader of what is now Dog God/God Dog. He's now the number two (for some dumb reason) and lied how Burn knuckle and company attacked him for no reason (because the new leader banned the swindling business and he would have been in deep shit for going behind his back). So yeah this whole arc is one big ass misunderstanding and could be avoided if Lee Jin Sung's (Zack) childhood friend wasn't so dumb to keep the former leader of his (forcefully) achieved gang still in his group and also in such a high rank.
Oh yeah I remember now. Ugh! This is so annoying. I love the story but I just can't stand the leader of the Dog gang
I'm so sick of these dog gang people (I forgot their gang name)! Leave Daniel alone! I forgot why their leader is even mad at him but I know that it's just a misunderstanding. Why are these gangs constantly bothering him? And that girl's dad and that guy in their company? Whatever tf his name is.