Mabel Tanaka is a slim, fair-skinned 19-year-old Anglo-Japanese-American college student of average height. She has short, messy, straight neck-length black hair styled in a thick shaggy bob cut, thick black eyebrows, monolid brown eyes, and scattered freckles bridging across her nose. Personality-wise, Mabel is a passionate, scrappy, and fearless animal lover who ferociously follows her heart. While she cares deeply for creatures big and small and is fiercely protective of local wildlife and natural habitats, she can also be impetuous, impulsive, and occasionally lose patience with humankind. Driven by a rebellious and determined spirit, she is willing to take extreme risks—such as using experimental technology to transfer her consciousness into a robotic beaver—to fight for those without a voice.

Dr. Samantha "Sam" Emily Fairfax is a tall and stout elderly scientist with fair skin, blue eyes featuring black winged eyeliner, light freckles, and wrinkles under her eyes. She has disheveled, shoulder-length wavy grey hair in a long bob cut, and wears half-moon tan glasses, a white pearl necklace, and matching pearl earrings. Her wardrobe consists of an unbuttoned white lab coat with a golden beaver pin on the right side of the collar, a button-up long-sleeve collared yellow blouse with light purple polka dots underneath, high-waist reddish-brown pants, and brown ankle boots. Personality-wise, Dr. Sam is full of nervous energy, deeply passionate about her work, and serves as the brilliant inventor leading the top-secret "Hoppers" research project at Beaverton University. Though she runs her lab filled with powerful technology with precision, she can easily become flustered when chaos strikes. She is conscientious and level-headed enough to respect the natural boundaries of the animal kingdom, and she genuinely cares about the safety of others, fiercely wanting to avoid any danger or total ecological collapse.

Dr. Nisha is a petite and slim, caramel-skinned middle-aged Indian-American scientist and college professor at Beaverton University. She has short and slightly wavy, chin-length dark brown hair styled in an old-money bob cut with slight grey streaks, brown eyes with thick dark brown eyebrows, and plump lips. She wears thin square-shaped golden glasses and an unbuttoned white lab coat with an ID card hanging out of the right pocket over a button-up collared white polo shirt, a knitted grey sweater vest, ribbed knit beige pants, and grey flats. Personality-wise, Nisha is Dr. Sam's astute, loyal, and composed colleague who serves as second-in-command at the top-secret lab. While she is on the quieter side, she treats their groundbreaking work with the utmost professionalism and is known for being brutally and uncomfortably honest with an unamused, deadpan delivery. Far more serious and solemn than her bubbly supervisor, Nisha maintains a dignified expression and keeps the lab grounded, though she deeply cares about the safety and well-being of others, including Mabel.

Conner is a biology graduate student and researcher working under Dr. Sam in her top-secret lab. Personality-wise, he is cheerful, gregarious, and quite awkward. Caught right in the blast zone of the high-tech animal mind-swapping experiments, he does not really know how he got mixed up in the chaotic mess and would very much like to find a way out of it. Physically, he is a Black man of African descent with short, neatly cropped dark hair and matching facial hair. He wears practical, low-key, lab-ready casual attire tailored for a research environment, and his appearance features wide-set, expressive eyes and an animated build that reflects his nervous, overwhelmed demeanor.

King George (also known as the Mammal King) is a larger-than-life beaver and the leader of the pond. Physically, he is a short, brown-furred beaver with thick fur, a beige belly, small beady black-dotted eyes, a rounded dark snout, large front teeth, small dark paws, a wide flat tail, and a simple gold crown on his head symbolizing his royal role. Personality-wise, George is undeniably optimistic, kind, jovial, and friendly, though anxiety and imposter syndrome have taken a toll on his hairline. A lifelong bachelor married to his job, he embraces his role with enthusiasm, leading group aerobics, learning everyone's names, and enforcing his core philosophy through his three "Pond Rules" to help everyone work together in harmony.

Mayor Jerry Generazzo is a tall and slim, fair-skinned middle-aged man with short dark gray hair swept backward into a clean pompadour, thick black eyebrows, brown eyes marked by a few subtle wrinkles, and a sharp, hawk-esque nose. He dresses in a sharp politician's wardrobe consisting of a tailored blue suit with a small American flag pin on the lapel, a crisp collared white dress shirt, a long purple tie, a black belt, and slip-on brown penny loafers. Personality-wise, he is self-obsessed, highly confident, and completely unbothered by the moral implications of his actions. As a slick real-estate developer running for reelection, he initially cares far more about pushing through highway construction projects that threaten local animal habitats than community ethics.