Kibitzer

Did I ask you what you thought about my cards, you kibitzer?

"Don't be a kibitzer!" Grampa snapped. "When I need help, I'll ask for it. No dad-blamed machine is gonna outthink Grampa!" He snorted indignantly.

Neither good nor evil exactly, he is the ultimate catalyst or kibitzer, a blue-note howl of pain and laughter such as Charlie Parker might have blown.