I finally got up from my desk, looked him in the face and started talking to him.
What do you want? I asked.
Why do you want that? I asked.
When he couldn't give me a solid answer about why he wanted me to fail, I told him to wait in the other room. He showed up for a couple of days after that, just to see if I'd let him back in. I didn't.
After this, I started answering every question with multiple answers. What is the Story Goal? To get Eric back on the team. To understand why Eric left the team. The find a logic behind the strange occurrences. So that's three possibilities right there.
When I realized there was more than one path forward from where I was standing, I also knew there was nothing solid enough to criticize, so there was no point in even starting.
In essence, if you have one answer, then it had better effing work, and few ideas can withstand that kind of pressure. But if you have a bunch of answers, you can relax, because then you can slide around any obstacle.