Crimson knows how to pretend to be kind and cheerful when necessary in order to create a good impression of himself (as he did when he first met the members of I.M.P.). However, this mask instantly comes off when it is no longer needed.
I’m a dignified man, well respected and properly feared as one of the few imps with power in the Greed Ring. I run my show, my crew, my profession. My mob. I’m a dignified man, well respected and properly feared as one of the few imps with power in the Greed Ring

Violent. Ruthless. crime boss. Controlling 

Skilled Torturer: As stated by Hairo himself, when he was a human, he was extremely skilled at torturing 
people using various methods. Hairo instinctively knew when someone was about to hit the limit, while he is alive. He even has the mindset of a person who enjoys inflicting pain and suffering on others.
Hairo appears to have immense anger management issues, coming to the point of him being "suicidal": shooting himself in the head to contain it. The main cause is presumed due to mistreatment 