Well, I've been mulling this over after noticing these little creeps cropping up more and more. In a lot of urban fantasy or gritty contemporary stuff, the devil rat feels like a walking symbol for all the rot we try to ignore. It's not just a pest; it's the physical manifestation of societal decay, right? They thrive in the cracks of our cities, in the forgotten tunnels, just festering. It's a shorthand for something being deeply, fundamentally wrong with the environment.
Take something like 'Neverwhere' by Neil Gaiman, or even the Rat Kings in various stories. They represent the unwanted truth bubbling up from the sewers. There's also a layer of them being survivors, too adaptable for their own good, which mirrors a certain cynical view of humanity. We're the ones who made the garbage they live in, so maybe they're our grotesque reflection.
Honestly, the most unsettling use for me is when they're not even magical, just...there. A swarm of them in a dystopian scene says more about the collapse than any monologue could. It’s a visceral, gut-level symbol of filth and consequence.