[-] JacobV suggested:
Nightmare Stephanie: Become what looks like a throwaway gag, only to end up being the main antagonist of the entire storyline.
Here's an idea, what if she became what looked like the main antagonist of the entire storyline, but ended up in fact being just a throwaway gag. Look, here's her in the future preparing to attack two people who will be main characters at the time; one whom we already know and one whom we do not. And now we're sure to never see or mention her again because the joke has reached its ultimate conclusion.