The problem I have is that the Ranger will then have to accept that the Daedra become part of his life. Especially Hiricine. One of the fundamental laws of the Rangers will then be ignored. Perhaps the Ranger can "fall" into the darkness where he still does the things the Rangers normally do, but with unconventional methods. One way to symbolize this is to change to a crossbow and primarily use those explosive rounds. This way you can also use Daedric weaponry if you are willing to invest in those perks. Finally you can also begin to use the more sadistic and destructive shouts, instead of the buffing. The Dark Brotherhood will be a good start to find Marked for Death.
The problem I have is that the Ranger will then have to accept that the Daedra become part of his life. Especially Hiricine. One of the fundamental laws of the Rangers will then be ignored. Perhaps the Ranger can "fall" into the darkness where he still does the things the Rangers normally do, but with unconventional methods. One way to symbolize this is to change to a crossbow and primarily use those explosive rounds. This way you can also use Daedric weaponry if you are willing to invest in those perks. Finally you can also begin to use the more sadistic and destructive shouts, instead of the buffing. The Dark Brotherhood will be a good start to find Marked for Death.