I don't know where the idea came from, and didn't even consciously wish for it, but as the leader's hand closed on my shirt it turned dark, and then seemed to crumble away. He blinked and looked down in confusion at a mass of cockroaches crawling over my shirt and the stump of his wrist. Then he screamed and stumbled back, shaking his arm frantically to get the bugs off. The arm got shorter as it continued to dissolve into insects, and he stumbled and fell as his feet and lower legs also began to break apart. The transformation sped up as he thrashed on the ground, crying out in terror as his clothes bulged and deformed, then collapsed. His screams cut off as his chest and throat broke apart, and then only his eyes remained for a moment, staring in horror until even they became small mounds of cockroaches that scurried off into the night.
I was still staring in shock when Runt said "Wow! That was pretty amazing." I turned to see him grinning at me. The rest of the gang was running away as fast as they could, screaming. I'd been so focused on the leader I hadn't even noticed them bolting. Knocking the few remaining insects off my shirt, I asked "Did I really do that?"
Runt nodded. "Yep. Thug to bug in one easy step. Well, maybe a few hundred thousand steps."
"I killed him?" I knew I should be horrified by what I had done, but I felt more curiosity than anything.
"Nah. He's still alive, but his awareness is split up among all those cockroaches. He'll gradually die as his bodies die, but as long as one of the roaches is alive he is too."
"What about the others?"
Runt shrugged. "I doubt they will ever bother anyone again. And they sure as hell won't tell anyone what they saw." He grinned. "That was class-A demon stuff there. You learn fast!"
"But I'm not a demon!"
Runt grinned. "Says the kid with the horns and tail."