Anyway, there never was a Multiverse. It was not vast, it was not wonderful and it was not destroyed. And still there are remnants, mementos of non-existent history. Trapped in the Void, they long for existence they never had, for memories they never lost. Sometimes, they claw their way into Reality, but they don't belong. They are not, like creature-shaped holes. They need to be filled.
You will think nothing of it and forget about them.
Time will pass and one day you will remember how silly you were, all afraid of imagined un-people. And there they will be again, suddenly standing in your peripheral vision. Your heart will skip a beat and you will jerk your head, but there are only normal people going after their business and no one strange or scary.
But you know you really saw something, something weird enough that it cannot be a coincidence. Why have you seen them and nobody else seems to take notice? Is there some sinister plot? Who is behind it? The government? Aliens? China? Or all of them together?
And thus the Neverwere grow.
Neverwas (pl. Neverwere)
Neverwere are not but they want to be, and they will grasp at any connection someone can give them to Reality. Neverwere are only encountered as a fleeting sight or an off-handed mention, never directly. If the players don't notice or let it go, forget, or ignore the tidbit, good for them. They just defeated the Neverwas.
If they start talking about it, if they make theories, the Neverwas grows more real. Every time it's remembered, it gains an HD or proliferates. Every connection or power that gets proposed is true (within reason).
What if these strange faceless people were somehow connected to the murders we were investigating?
Sure, they are now and they always were.
No, wait, what if the wizard we pissed off sent them?
Once Neverwas gains a goal, it will start working towards it, incorporating any new powers or goals or connections as they pop up. Contradictory or paradoxical goals are not a problem, Neverwere are not creatures of logic and reason.
If the players can guess the nature of this absorption of concepts, they can turn it against the Neverwere.
Are they weak to fire?
Of course they are.
Are they afraid of cheese and bawdy songs?
This is the other way to defeat Neverwere, apart from ignoring them.
- If a player asks you about some background NPC whose name they have forgotten, tell them he was completely unremarkable. They can remember nothing about his appearance, race, clothing, or ... nothing at all, really. Or wait, was it a woman? Have they actually ever met such an NPC?
- Everywhere a PC goes, they keep getting letters. The envelope always has the address of their current location in nondescript writing, but inside is only a blank sheet of paper.
- A house where every picture had the faces erased. And in the bookcase, all books are filled with just a single word, repeated over and over and over again.
- Featureless silhouettes are watching the party from behind every window on the street. Nobody else seems to pay any mind to it.
- Someone familiar who should have been dead or definitely not here bumps into a PC, but before they have a chance to react, that someone is already lost in the crowd.
- A word or a symbol keeps showing up. Nobody knows why, or what it means. If the PCs decide to investigate, that word or symbol will be present every time they think to ask.