Hadler's character development was superb, from being a ruthless maniac to becoming a force of justice and honor, seeing him cry and pray for Popp was one of the greatest anime moments ever, redemption at its best.
I did not expect Hadlar to be this amazing. I thought he was going to be your typical Dragon Quest bad guy but he ended up being so much more. Hadlar and Popp are the best lol
Normally a main villain-like antagonist would turn them self into a grotesque monstrosity and become more unhinged in the process, however hadlar felt like he instead improved both physically and mentally as a warrior at the cost of his own lifespan.
Hadlar is crutel indeed, but he is always a fair fighter. He hardly uses dirty tricks, and tends to face his worthy opponents, Avan and later Dai, himself. He isn't a really good guy, but at least his fighting spirit is respectable.