You know how in the final fight with Berkut he mentions something along the lines of "Power doesn't betray me."? Well it kinda got me thinking. He's seen as really really unstable towards the end of the game, and I connected some dots to make a headcanon.

He has got to have something aside from Rinea to make him not so upset so much. Then I took one look at Rinea's design and something clicked in my Window's 98 computer of a brain. 

Fucker probably has a doll somewhere hidden that he just vents to after things when he doesn't want to deal with the servants and or Rinea. 

Think about it, a doll can't betray him, nor can it judge you so....

+Adding this to my random book of headcanons to make a Yan!Berkut fic.