Walter is a fundamentally good, confrontation-averse attorney and environmentalist who leaves corporate law to work for the Nature Conservancy. Raised in a challenging household, he is fiercely dedicated to being a better man than his father and to pleasing his wife, Patty. His primary passions include bird conservation and combating overpopulation, though his generous nature occasionally leaves him feeling like a reactive participant in his own life.

Patty is a former star basketball player who languishes as a stay-at-home mother in St. Paul, Minnesota. Having built her life around fierce athletic competition and an urge to outdo her politically connected family, she struggles to find purpose once her children grow older and more independent. Her boundless freedom often manifests as restlessness and depression, leading her to feel disconnected from her husband's simple goodness.

Richard is Walter's long-time best friend and a fiercely independent indie rock musician. He is a charismatic, womanizing artist who struggles with substance abuse and deep-seated self-loathing. He strictly guards his anti-corporate music principles, viewing his eventual commercial success as a source of humiliation rather than pride.

Joey is Walter and Patty's fiercely independent, entrepreneurial teenage son. Defiant of his parents' liberal values, he aligns himself with right-wing politics and fiercely guards his financial and personal autonomy. He possesses a manipulative streak, eagerly accepting the unquestioning devotion of his girlfriend while constantly seeking new, exciting opportunities to advance his own ambitions.

Jessica is the older child of the Berglund family. She largely exists on the periphery of her family's intense emotional dramas, providing a relatively stable contrast to her volatile brother and restless parents. She occasionally voices her desire for more attention and affection from her parents, demonstrating an independence that does not require constant rebellion.

Lalitha is Walter's passionate, hardworking assistant who shares his intense dedication to environmentalism and combating overpopulation. She harbors a deep, unambiguous admiration for Walter exactly as he is, contrasting sharply with the complicated demands of his family life. Her perspective offers a non-western viewpoint on American environmentalism and activism.

Connie is the daughter of Carol Monaghan and Joey's intensely devoted girlfriend. She possesses an unwavering, unquestioning loyalty to Joey, molding her own life choices—including her education and finances—entirely around his needs. Her absolute malleability leaves her highly vulnerable to his whims and ambitions.

Carol is the Berglunds' neighbor in St. Paul and Connie's mother. She maintains a tense, outwardly polite but internally hostile relationship with Patty, finding some satisfaction when the outwardly perfect Berglund family experiences internal strife. She acts as an occasional voice of reason regarding Joey's mistreatment of her daughter.

Eliza is an unstable, manipulative student who essentially stalks Patty during their college years before becoming her closest friend. She flatters Patty intensely while attempting to isolate her from her other social circles, establishing a controlling and emotionally volatile dynamic fueled by drug use.

Jonathan is Joey's college roommate, a young man from a prominent, right-wing Jewish family. He frequently debates politics with Joey and serves as a moral compass regarding Joey's treatment of Connie and his increasingly murky business dealings in war profiteering.

Jenna is Jonathan's stunning older sister and a symbol of wealth, status, and carefree excess. She captivates Joey with her beauty and her proximity to high-powered finance circles, representing a tantalizing temptation away from his established life and relationship with Connie.

Joyce is Patty's mother and a successful, professional Democrat and state assemblywoman. She is deeply invested in her political career and social standing, which often leads her to handle family crises with an eye toward public optics rather than maternal warmth.

Ray is Patty's father, an attorney who frequently works for underprivileged clients. He possesses a cynical view of the world and often teases his children with a sharp, borderline cruel sense of humor that masks his deeper, unexpressed affections.

Vin is a wealthy coal magnate who loves birds but prioritizes his lucrative business interests. He uses environmental conservation as a strategic cover to secure mining rights, leveraging powerful political connections to achieve his goals in West Virginia.

Kerry is a pragmatic, morally flexible war profiteer subcontracted by LBI. He is entirely focused on financial gain, eagerly pushing Joey to source antiquated military truck parts regardless of their quality, legality, or safety for the soldiers using them.

Coyle is a hostile, obstinate West Virginia local whose land is targeted for mountaintop removal. He fiercely resents wealthy outsiders dictating the fate of his region and serves as a direct catalyst for Walter's mounting public anger.

Linda is an Evangelical neighbor at the lake development where Walter eventually resides. She staunchly defends her right to let her pet cat roam free, becoming a frequent target of Walter's aggressive bird-conservation campaigns.

Bobby is Linda Hoffbauer's outdoor cat. As an instinctual predator, he continually hunts the local bird population, making him the primary nemesis in Walter's ongoing crusade to protect neighborhood wildlife.