How does anyone think the ML is a green flag? He killed the MC's master and childhood friend, he also threatened and beat several others. Or had them killed/beaten. He is hiding his identity from the MC.
This is a red flag, not green. He is possessive, obsessed and jealous to the extreme. He does not want MC to talk to anyone else or mention anyone else by name.
This is one thing I never really get. Why isn't the MC telling the ML what happened? It concerns him as well, as they threatened to expose him, so there is no explanation that it is not the ML's concern. There is no good reason not to tell him! Hiding it just to create drama is so annoying.
I mean he has explained many times and Taeshin thinks he can solve all of Wonwoo’s problems. He doesn’t want to take advantage of Taeshin’s money and he doesn’t want to use him. He still has his pride and it’s important to respect that. He’s trying to keep his head above water because he’s scared of Taeshin leaving him if he becomes too much of a hassle or too boring.
But the threat made was to harm Taeshin, he has the right to know. Keeping that information from him because of pride or fear of abandonment is just extremely selfish.