It's just that he had learned to swallow his suffering. He tried to hide it, even more so when he was on such an important mission. He didn't like to talk about it, but at the same time, he liked it.
He wanted to become a person who could take revenge and never forget who he took revenge on, but at the same time, he wanted to remember them without feeling so much pain. That's why he talked about it so naturally. He believes that the more he talks about it, the less pain he will feel every time he remembers it.
His mind and way of thinking are simple but perhaps effective.
Klaus noticed this, so he nodded.
"Remembering things from the past can sometimes serve to make you more resistant to pain, but don't do it. It will do you more harm than good."
Though surprised at his response, Carion looked up to question him. "Why?"