Kristen is an independent business owner who designs and sells clothing for tiny dogs. She suffers from extremely painful uterine fibroids and anticipates needing a hysterectomy soon, a medical reality she keeps hidden from her friends and boyfriend. She is highly sarcastic and witty, often using humor to deflect vulnerability and maintain her emotional distance from others.

Josh is a firefighter who recently moved from South Dakota to California to work at the same station as his best friend. He comes from a large family with six sisters and strongly desires to have a big family of his own. He is patient, observant, and handy, quickly taking on a carpentry job building miniature stairs for Kristen's dog boutique.

Sloan is an artist and Kristen's best friend since high school. She is demure, idealistic, and deeply romantic, serving as a distinct contrast to Kristen's brash personality. She eagerly anticipates her upcoming wedding and provides a constant source of unconditional emotional support for Kristen.

Brandon is a former Marine turned firefighter who works alongside Josh. He is preparing for his upcoming wedding to Sloan and frequently acts as a stabilizing presence for the people around him. He is dependable and offers steady, mature advice to Josh regarding his complicated feelings for Kristen.

Tyler is an active-duty Marine who maintains a long-distance relationship with Kristen, only seeing her in person for a couple of weeks each year. He is handsome and enjoys sophisticated dining and cultural events. He does not wish to have children, a stance that conveniently aligns with Kristen's hidden medical reality.

Evelyn is Kristen's mother, a successful lawyer and law professor. She became pregnant with Kristen in her forties, an event that derailed her career plans, and she continues to hold onto this resentment. She frequently criticizes Kristen's choices, demanding a level of perfection that creates a permanent emotional distance between them.

Stuntman Mike is Kristen's tiny, fierce dog. Named after a character from a Quentin Tarantino film, he is notoriously picky about the humans he tolerates. He frequently barks aggressively at Tyler but immediately warms up to Josh.

Shawn is a firefighter who works at the same station as Josh and Brandon. He is highly vocal about his physical attraction to Kristen and frequently offers Josh unsolicited, often misguided advice on how to handle romantic relationships.

Celeste is Josh's ex-girlfriend from South Dakota. Their relationship ended primarily because she had no interest in having children, fundamentally clashing with Josh's lifelong dream of raising a large family.

Amanda is a woman Josh meets while running an errand with Kristen's dog. While she is pleasant and attractive, their date quickly makes Josh realize his total lack of romantic interest in anyone besides Kristen.