Akira

Another reason Fyodor Dostoevsky is not dead:
          
          Ability:
          We don't know what his ability is- we only know how he touched a governmental armed policeman which caused him to die, we also saw this with karma.
          
          An ability theory:
          What if his ability was to control life and death. The demon Fyodor sounds like someone who has something to do with death; as we have seen. If his ability was to do with life and death then as well as being able to kill with touch, he could also control imortality like I suggested. 

Reasons Fyodor Dostoevsky is not dead: 
          
          Why him I?; Well we know how dazai has been trying to kill him and stuff and we all have heard the saying 'blah blah dazai enemies blah blah dazai enemies blah blah' but fyodor had the same mindset as dazai making them equal foes. 
          
          Why him II?; Why not fritzergerald, or Mori, or fukuzawa who run other businesses.. Why havent they also killed off Lucy, haguchi or ranpo ect?
          
          What could save him?; We have seen the part of his ability where he can kill who he touches, but we also know about there being more.. This gives us the chance of something else being his ability- remember season three with ace? What if that is something to do with his ability, he just put the props to make it look like he was just being smart- let's also think about how he would've gotten away with the antidote if his hand wasn't injured at all- he wouldn't of asked for assistance and then proceeded to be attacked.. He would've survived leaving dazai to die-
          
          Was it really him? - A theory I have (with no proof) is; what if that wasn't fyodor? Yet again, we don't know his ability but we do know about the page which is in their (the decay of Angel's) possession making anything possible!