direct the transformation

"Do you remember what you did?" The words had an edge to them, but at least I didn't say, "Do you remember murdering Kim Delaney?" Who says I can't be diplomatic?
MacFinn shuddered. "Pieces," he said. "Just pieces. " He looked at me and said, "I didn't mean to hurt her. I swear to you. "
"Then why is she dead?" The words came out flat, cool. Tera glared at me, but I watched MacFinn for his answer.
"The curse," he said quietly. "When it happens, when I change - have you ever been angry, Mr. Dresden? So angry that you lost control? That nothing else mattered to you but acting on your anger?"
"Once," I said.
"Maybe you can understand part of it then," MacFinn said. "It comes on me, and there's nothing left but the need to hurt something. To act on the rage. I tried to tell Kim that the circle wasn't working, that she had to get out, but she wouldn't listen. " I heard the frustration in his voice, and his hands clenched into fists. "She wouldn't listen to me. "
"It frustrated you," I said. "And when you changed . . . "
He nodded. "It's how I came back from 'Nam. Everyone else in my platoon died but me. I knew the full moon was coming. And I knew that I hated them, hated the soldiers who had killed my friends. When I changed, I started killing until there wasn't anyone left alive within maybe two miles. "
I stared at MacFinn for a long moment. I believed that he was telling me the truth. That he didn't have much control, if any, over his actions when he transformed. Though it occurred to me that if he wanted someone dead, he could probably point his monster-self in the right direction before he lost control.
Note to self: Do not cut MacFinn off in traffic.

Fool Moon Chapter 15, Page 164-165