There is another factor in play. For once in his life, he's not in the middle of a war. He can reasonably expect there will be a tomorrow, a next week, a next month, or even a next year.
It is now very clear Varilik is the manipulator Ain has warned about. He's massaging all of Fenn's feel good buttons, getting him drunk, and offering his bed. The wedge is getting bigger in real time.
I am beginning to believe this unnatural detachment Fenn has with causing death is directly linked to his shadowforger powers. This lack of empathy is the true crux of shadowforger horror stories.
"Looks like he fell."
A brick seems solid, immutable, and impenetrable. But bricks can shatter and turn to dust. Clovis shattered Brick merely by responding to his violence. Brick is both history and erased.
Varilik's plan is becoming clear. He's slowly driving a wedge between Ain and Fenn. Ain has waited too late to reasonably inform Fenn of how manipulative and dishonest he can be.