Yandere Fyodor

Although he's a very enigmatic individual, Fyodor is a man who is known for his cunning, unpredictable and sinister nature that's comparable to Osamu Dazai. He is regarded as a monster by his enemies. He is composed and confident, and even in dire situations, he hardly falters and doesn’t appear to fear his enemies, conjuring conniving plans and strategies that result in his success. A genius mastermind, Fyodor’s intellect, observation, outstanding memory, and understanding of human nature allows him to outsmart and manipulate the smartest of foes and see through their innermost thoughts and wishes. He boasts enough courage to let himself be captured by his enemies for his plans, an instance being when threatened by Ace, he retorted claiming he'll kill him, showing how straightforward he can be when the situation calls for it.

Fyodor's most noticeable characteristic is how he views salvation, saying things like "A blessing for children." and how God wants perfection and harmony over anything else, all while committing cruel and unforgivable acts of terrorism in nonchalance. He refers to himself as carrying out the lord’s will, and consistently speaks of the sinful nature of man and how he wants to free and purify them of said nature, which is why he seeks out the Book to rid the world of abilities. Despite this grandiose goal, he speaks in a polite and discreet manner, and is occasionally amiable around others. Ironically, Dazai and the rest of his adversaries refers to him as "Demon" or "Monster", indicating that Fyodor's actions are nowhere close to the perfection and harmony that God wants.

When it comes to his subordinates from the Rats in the House of the Dead and his associates from the Decay of the Angel, Fyodor views them as pawns in his overall planes, deceiving, exploiting, and manipulating them. He neglected Nathaniel Hawthorne’s wish to save Margaret Mitchell by brainwashing him and erasing his memories of everything other than her, using his desire to save her for his own benefits. When Sigma finished playing his role at the Sky Casino, Fyodor betrayed him out of nowhere by having Nathaniel attempt to assassinate him, which even took Atsushi Nakajima by surprise. Dazai even stated that Fyodor would have killed Sigma if he hadn't chosen him to be his helper during the prison break. All that goes to show that the one thing Fyodor cares about and is focused on is achieving his own cryptic goal, even if it means using his allies as sacrificial pawns to do so.

By the time he took over Bram Stoker's body, Fyodor starts to show how much of a threat he truly is, how very little he cares about the lives of others and how he views everyone as just a means to an end. The world-renowned hero Ōchi Fukuchi; despite being the leader of the Decay of the Angel, was being manipulated by Fyodor into starting the global terrorism plot in the first place and his decision of sacrificing no more than 500 lives was a plan that Fyodor himself concocted In the end however, all of Fukuchi's actions were only part of Fyodor's scheme of turning the Hunting Dog captain into a being with godlike powers and even after manipulating Fukuchi into enacting terrorism on the entire world in order to prevent a world war in 36 years, Fyodor shows no guilt over making Fukuchi's tribulations during the terror plot be all for nothing and even smugly reveals that the world war he was trying to prevent was a lie he made up.

Overall, Fyodor is a self-interested, manipulative, and enigmatic man whose manipulative tactics relies on the desires and goals of others rather than loyalty, respectful leadership, or genuine friendship. As Dazai suggest, Fyodor doesn't trust anyone he can't manipulate which is the sole reason why doesn't have any genuine friends or allies.