Ranger is an older bloodhound who lives a neglected life chained under a shack in the deep woods of East Texas. Stolen as a puppy and later shot in the leg by his cruel owner, he is deeply lonely. His sorrowful howling attracts the attention of a wandering cat, leading to an unexpected bond that gives him a renewed sense of purpose as a protector.

The Calico Cat is a pregnant, abandoned pet who enters the forgotten forest seeking shelter. Drawn by the mournful howling of a hound, she takes refuge in the space underneath a run-down shack. She forms a surrogate family with the dog, relying on her hunting skills and maternal instincts to provide for her upcoming litter while avoiding the dangers of the forest.

Gar Face is a bitter, violent man who lives in isolation by the Bayou Tartine. Disfigured during a childhood trauma involving his abusive father, he harbors deep resentment toward the world and takes pleasure in inflicting pain on animals. He spends his nights drinking at a local tavern and his days hunting for pelts to sell, hoping to earn the respect of the local trappers.

Grandmother Moccasin is an ancient lamia, a mythological creature sharing the blood of a human and a serpent. Having lived for thousands of years, she waits in a buried clay jar as the tree roots holding her slowly decay. She carries immense anger over a past betrayal involving her family, biding her time until she can enact revenge.

Sabine is a silver kitten born into the harsh environment of the Little Sorrowful Creek forest. Named after a beautiful river, she grows up in the "Underneath" with her family. She learns to hunt small prey while adhering strictly to warnings about the dangers of the open world above.

Puck is a silver male kitten whose natural curiosity constantly tempts him away from safety. Named for his playful and mischievous demeanor, he struggles to obey the strict rules set by his mother to stay hidden. His yearning to explore the warm sunlight places him at direct risk from the predators of the forest.

The Alligator King is an enormous, hundred-foot-long reptile who has ruled the bayous for over a millennium. Patient and practically invincible, he observes the foolishness of humans who attempt to hunt him. He serves as an ancient guardian of the waterways, commanding respect from the animals and the few humans aware of his existence.

Night Song is a lamia who once lived in the forest with her mother, filling the woods with beautiful lullabies. Her desire for a life beyond the bayou leads her to fall in love and assume a human form, a decision that permanently fractures her relationship with her mother and sets a tragic chain of events in motion.

Hawk Man is a mythical being who originally possessed a bird form before falling in love with a lamia. He chooses to take a human shape to build a family with his wife, joining an Indigenous settlement near the creek. His devotion to his family puts him directly at odds with his vengeful mother-in-law.

The Hummingbird is a mysterious, glowing creature that flits between the physical world and the spiritual realm. She appears during moments of extreme peril, serving as a guide and messenger. Her sudden appearances act as vital warnings for the forest's inhabitants.