From what we can see, the young master seems to invoke feelings of lu** and envy, and seems to see through people's facades and use it against them, and loves to take away people's precious things away from them.He doesn't like the butler since he doesn't seem to react much to his actions and only sees him as an owner pleasing loyal dog.The butler is afraid of losing his value,and does anything to please his owners, so when he was told that his master expected more from him, his desire to please them increases, The young master constantly uses June to get a reaction with him, and toy with him, hence why he agrees to the young lady's request. The young lady herself seems ashamed as she finds herself feeling desire towards her brother, which he holds over her.However, at the same time, she is aware that he holds ill intentions, hence wants to prevent that. The true intentions of the young master remains a mystery, but the fact that it is nothing good is established. The young master loves dangling and toying with people's desires, precious things and their insecurities and uses it to get an upper hand over them.The green and emerald I think , personally, symbolizes envy and negative insecurities.