That’s exactly what I thought. We get to feel what Garam feels, having trouble remembering why we hate him (￣∇￣") , but I like how the author keeps showing how his actions had consequences in other people’s life, even as we warm up to him. Other stories tend to sugarcoat the character’s actions to make it more likable, but in this one heejae is very human precisely because we know his flaws.
Truly, it's very rare for story to actually acknowledge a character actions at face value. As you said we know his flaws and the author has presented them as they are. I also like how the author also allows us to chose how we feel about him. I find that with other characters like him, their authors tend to want us to feel a certain way about them.
I am currently so obsessed with this story and one of the things I genuinely find interesting as I read this is how I as a reader have warmed up to Heejae despite his actions and the way treats his students. Just like Garem I too, can't seem to hate him. What I like about this it's that the story constantly reminds me that Heejae isn't a good person though how many characters have to remind me that he's an ass hole but he is so captivating and interesting as character that i forget.