To me though, the prior contractor was already portrayed as arrogant though from chapter 1. He signs a contract with a talking book out of curiosity, and then abandons the book after he has second thought. That's not cinnamon roll behavior, that's entitled rich kid behavior.
He even had the audacity to say to a potential psuedo god: "You already waited 300 years, just wait until I die."
What do you expect to happen. This is the exact type of arrogance that gets people cursed or killed in stories involving gods.
It even has integrated moral in the story in "Watch what you say or it might come back to haunt you" and "Don't abandon duties you signed up to do". I could definitely see this being some twisted bedtime story.
Not sure how I feel about this reveal, on one hand I'm glad our protagonist didn't kill this cinnamon roll cute kid, on the other hand, it feels like a cheap attempt to avoid any moral gray areas.