When my wife (at that point my partner) and I finally arrive home with the pet carrier after a trafficky drive to and from Connecticut (complete with an obligatory stop to tour the Mark Twain House), we look at each other and wonder what we’ve done. In it, three rambunctious rescue rats bounce around like excited, furry pinballs, eager to see what their new home has to offer. Finally, we release them into what can only be described as a rat palace: a spacious, two-story cage on wheels aptly named the Midwest Deluxe Critter Nation and decked out with every hammock, ladder, and hidey-hole the internet told us to buy.

The trio of sisters, one brown with a splash of white on her belly and white booties, one half brown and half white, the rat version of a black and white cookie, and one pale tan, smaller, softer, and smarter than the others (and clearly destined to be trouble), hesitate for only a moment, lining up shoulder to shoulder in the entrance of the carrier to survey the scene as the door swings open. Then, they’re off. They bound inside the cage and immediately launch into a sniffing and climbing tour, scaling the metal bars of the walls, leaping from level to level, poking in and out of every corner, and scampering from end to end on a mission to locate food bowls and water bottles and toys. By nightfall, they’ve transitioned to light construction projects, chewing and tearing and moving paper and plastic and fleece to redesign the space to their own ratty specifications.

We hover in front of the cage and marvel at these tiny, curious creatures that now belong to us. Somehow we’d both made it into our mid-30s without ever having a pet as an adult, and when we discovered that we both had pet rats growing up, our fate was sealed. It took a surprisingly rigorous application process through Mainely Rat Rescue, a flurry of online ordering, and a Sunday drive to Connecticut before we were officially rat moms to three 6-month-old girls from an abandoned “oops litter.”

Almost immediately, our lives settle into a new routine. Our evenings are restructured to accommodate cage cleanings, playtime, and couch lounging with our “pocket puppies,” as they’re called by rat enthusiasts. Our phones fill up with photos of Brown Bear napping in her hammock, Jupiter munching on tasty treats, and Luna plotting her next transgression. We introduce our friends—who run the gamut from fully enthusiastic to mildly interested to politely fearful—to our pets. We finally find an exotics vet who is accepting new patients, and who seems as charmed by our “spicy, busy ladies” as we are. We join a community of people united by their commitment to loving these small, charismatic animals with devastatingly short lifespans. Before long, we can’t remember a time before rats.

Life throws us twists and turns, as it always does. My partner starts a new job with more responsibility and longer hours, leaving me feeling isolated as I work from home every day. Like any overly ambitious bicoastal couple, we plan a wedding on each coast, and officially tie the knot. We care for family through sicknesses and surgeries, support friends through divorces, career changes, and new babies. We start the complicated process of trying to have a baby of our own.

And yet, no matter how stressful the day is, no matter what news we’ve gotten, our rats are always there, shiny-eyed and ready to play, climbing excitedly to the top of the cage for snacks and scratches as soon as we open the doors. It occurs to us that this is, of course, why so many people have pets in the first place. But somehow it feels different to love pets that most people consider pests. They seem to expect nothing of us—instead, they are just happy to exist in a safe space free of hoarders, hawks, and snakes. And perhaps it is this unassuming warmth and openness that makes us feel so compelled to give them so much in return. We become determined to make their tiny lives as wonderful as we can, which seems like the least we can do in exchange for the outsized joy they bring us.

As the weeks and months pass, my wife and I become those people we’ve never understood: the ones who sing songs to their pets, who pore over pet photos while on vacation, who recount pet stories to friends over dinner, who rush to greet their pets as soon as they walk in the door at night. We realize that these three furry girls have rearranged our lives and expanded our hearts in so many ways we didn’t expect—and the change, it seems, is permanent.