The longer Hao Ren knew Y'zaks, the less demonic Y'zaks seemed to be. He was more like a thinker and a philosopher, and maybe even a scientist. The rough guy had more profound knowledge than many scholars—a result of constant exploration and the long-term influence by a real scholar. This had become part of him.
Even if it was a demon, focusing on one thing for several hundred years would cultivate an amazing habit.