Monster of the Week: Cranium Rats

Last week I had the chance to pick up the latest Dungeons and Dragons 5th edition sourcebook, Volo’s Guide to Monsters – with a name like that, how could I pass it up? – and whoa man does that book make me want to gather up a group of unsuspecting players and hurl eldritch monstrosities at them.

I mean, uh… play D&D with me, guys! It’ll be fun, I swear!

Even a quick skim is enough to confirm that Volo’s Guide is right up my alley with monstrous player characters, a boatload of psionic baddies, and the entertaining footnote battles between Volo (think Steve Erwin) and his more academic publisher, Elminster. I knew the moment I laid eyes on this book that it would fuel more than a few blog posts.

But where to start? With my perennial favorites, the mind flayers? Or any of the creatures born from the nightmares of an equally terrifying psychic cyclops, the beholder? What about the monstrous fey creatures in the book?

Then a particular entry caught my eye, one as funny to me as it is eerie. I knew it had to be the cranium rat.

Okay, so, what besides the exposed brain makes the difference between an ordinary rat and a cranium rat?

I’ll let Volo’s Guide explain:

Mind flayers create cranium rats by bombarding normal rats with psionic energy. Cranium rats are no smarter than ordinary rats and behave as such. However, if enough cranium rats come together to form a swarm, they merge their minds into a single intelligence with the accumulated memories of all the swarm’s constituents. The rats become smarter as a result, and they retain their heightened intelligence for as long as the swarm persists.

Yeah. They’re magical psychic rats.

Are you laughing? No? Okay, how about this: “As a bonus action, the cranium rat can shed dim light from its brain in a 5-foot radius.”

I mean – they can see in the dark. That’s just gratuitous. It’s like the magical rat version of mustache-twirling.

But lest we dismiss them for their theatrics, let’s just glance at some of the spells that a large swarm can cast: command, detect thoughts, dominate monster.

Yes. The swarm of psychic rats is not just smart enough to deliver creepy, collective thought-speeches about how we have come for the cheese, foolish human, it also knows who you had a crush on in the third grade.

Of all the terrifying creatures – in this book alone! – that can read your mind, somehow swarm of rats is the one that I least trust with that kind of sensitive information.

Oh, but that actually doesn’t matter – because the rat swarm reports back to those other terrifying mind-readers. That’s right. The rats just reported back to the elder brain and all of the mind flayer cultists that serve it, and now they’re all laughing at you. One of them is probably writing an entry in the mind flayer burn book, because that has to be a thing.

The burn book from Mean Girls.
With great power comes great responsibility, mind flayer Regina.

In all seriousness – yeah, it definitely adds to their creep-factor that they report back to more intelligent and nefarious creatures, but they remain pretty eerie without that element. Chances are this is not the first time you’ve read about an entity with collective intelligence from sci-fi, fantasy, or horror.

There’s a reason for that.

Why do we find groups with shared consciousness so inherently creepy?

Two reasons: because it’s so alien, and because it’s so familiar.

First, the alienation. Speculative fiction writers have a long history of imagining states of being that are fundamentally different from our own. Humans are not capable of connecting to other beings on a mind-to-mind level – the purest type of connection, the fullest understanding that many of us can imagine. It’s no accident that this trope comes up so often: so much of human conflict is because of miscommunication and misunderstanding. We’re drawn to this type of psychic connection as a fictional device because it could bring us into harmony with each other in a way that our species is fundamentally incapable of doing.

It repulses us for the very same reason.

Stories that feature this kind of collective consciousness often portray a trade-off between an individual’s autonomy and the group’s consensus. The more unified the group becomes, the more each member loses of themself.

You don’t need psychic powers to understand that. It’s a fundamental struggle of living as an individual in a larger society. From speculative fiction to fiction without fantasy elements and even in our non-fiction and philosophy, these struggles are everywhere.

That’s why it’s so familiar. A swarm of psychic rats is scary for the same reason as an angry mob.

Of course, it’s also scary because they are rats and they spread disease and we’ve been strongly conditioned to be afraid of or hostile towards them for being vermin.

Vermin with shiny brains.

So make sure that you keep your trash fully contained – along with your psychic energy.

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