There's a vague character reference one in characters in a group of fanfic entries, but in addition is a non-character reference so you wouldn't know which was the actual spoiler. And again it's in a fanfic description of characters so as long as you avoid reading the character lists there, you're absolutely fine.

I was thinking just Ten, but I don't see why an AU Nine couldn't happen, so I'll add that to the rules this weekend. (Maybe even some sort of image of Niner added to the banner.)