The first time I saw Mon3tr's posture and fighting style in Karhi, the kingslayer showed extreme panic when facing Karhi.
The Kingslayer called Karhi a traitor and claimed to have killed Alex and Misa's father with the help of Alex (Sergey, who repented before being killed by the Kingslayer).
Later, after learning part of the truth, Karhi let him go. In chapter 8, the regicide realized that he was stronger and decided to return to Syracuse and handed over the remnants of the integration movement to Jiu.