Hearing the way the man addressed both of them, Jun almost laughed out loud. He never liked being called boss, so he always told his men to call him either brother or Jun. Everyone complied with his request and sometimes they even ended up calling him both, like this man just did.
However, when it came to Hyeon, no one dared to call him anything but 'Boss'. Despite the young man repeatedly admonishing them about this, saying he wasn't their official leader, no one seemed to listen. It's true that Jun was their boss in name and title, but Hyeon was their Ice Boss in action.
Either because of the young man's serious attitude or his extraordinary skill in maintaining proper order inside the group, every single one of the men agreed on Hyeon's title as the 'Boss'. As such, they always called him that out of respect. Granted, this respect was tinted with a generous amount of fear as well, making Hyun both loved and sometimes hated in the smugglers' group.