Yes, he really is the definition of don't judge the book by it's cover! He is all bubbly and kind, he readily gave his whole heart to an asshole like that, but he's actually well aware of his position and the set boundaries. And love that he does not get flustered and can tell people off when needed.
You know, I think he is also knowingly using this situation and Mr.Yeon to his advantage. He is using Mr.Yeon for his emotional needs and maybe that's why he is acting so in love with him - because when they're together, Yeomin can feel safe and forget his problems for a bit.

i love yeomin... such a strong character with a backbone despite his kindness and appearance. He doenst let others walk all over him, and he's super aware of things regardless of how others percieve him. He's so smart and quick witted in my opinion. Such a hard working character too.... I love you yeomin... I hope ur dad dies soon can mr. yeon quickly get rid of him pls.... ALSO YEON TAESOO GET UR HEAD IN THE GAME AND START BEGGING AND CRYING