Goust is introverted, often unemotional and callous. But there are reasons for that. He suffered so much when he lost someone dear to him or when his only friend betrayed him. That's why he decided not to get attached to anyone else except his brothers. He cares about them very much and worries about them. But he can't talk about his experiences, I think his brothers and Tan have suffered a lot. And it's ruining him from the inside out.