Grow in power

I had a flash of insight. "Shiro is one of them. That's why Nicodemus was willing to trade me for him."
Forthill nodded and closed his eyes for a moment. "Likely. Though the Denarians grow in power by inflicting pain and suffering on others. They become better able to use the strength the Fallen give them. And they gain the most from hurting those meant to counter them."
"He's torturing Shiro," I said.


Death Masks Chapter 27, Page 234-235