Cat is an intense, competitive marketing executive for a chocolate company. As an identical twin to Lyn and part of a triplet set with Gemma, she struggles with jealousy, particularly regarding her sister's ability to conceive a child effortlessly. Her structured life shatters when her husband confesses to a casual encounter, leading her to react with extreme, sometimes destructive anger.

Lyn runs a successful gourmet brunch business from home while balancing the demands of raising a toddler and a teenage stepdaughter. She shares Cat's physical features as her identical twin but maintains a hyper-organized, rigidly controlled lifestyle to cope with stress. Her desperate need for perfection pushes her to the brink of exhaustion and triggers severe panic attacks that she tries to keep hidden.

Gemma is the fraternal triplet, distinctly taller and red-haired compared to her identical sisters. She works as a professional house-sitter, drifting from place to place without a clear sense of direction or ambition. Haunted by the sudden death of her fiancé years earlier, she actively avoids commitment and routinely abandons romantic partners at the first sign of conflict.

Maxine is the mother of the triplets, having given birth to them at the age of nineteen. She heads an organization for mothers of multiple births, using her harsh, no-nonsense approach to dispense parenting advice. She often struggles to show warmth to her adult daughters, viewing their dramatic lives with stern disapproval.

Frank is the triplets' father, known for his happy-go-lucky and sometimes irresponsible nature. He divorced Maxine when the girls were young but has remained an active, if slightly immature, presence in their lives. He often acts as the fun parent in direct contrast to Maxine's strictness.

Dan is Cat's husband, a corporate professional whose sudden admission of an affair throws their marriage into chaos. He appears increasingly detached from the relationship, tired of Cat's intense focus and emotional volatility. He seeks an exit from the marriage long before he officially states it.

Michael is Lyn's husband, characterized by his patience and excellent listening skills. He tries to act as a stabilizing force in Lyn's frantic life and worries about her deep enmeshment with her sisters. He balances caring for his toddler with managing his resentful teenage daughter from a previous marriage.

Nana is the triplets' grandmother. She lives alone and maintains a cheerful, lighthearted demeanor despite the early stages of dementia clouding her memory. She acts as a comforting, uncritical presence for her granddaughters, particularly Gemma.

Charlie is a professional locksmith who meets Gemma entirely by accident. He is patient and clear about his intentions, making him a direct opposite to the men Gemma usually dates. He tries to push past her habit of abandoning relationships at the six-month mark.

Angela is the woman involved with Dan. She is unexpectedly polite and ordinary, which deeply frustrates Cat, who wants to view her strictly as a villain. She finds herself entirely caught up in the explosive drama of the Kettle family.

Kara is Michael's fourteen-year-old daughter. She carries a lot of teenage angst and directs most of her hostility toward Lyn, feeling fiercely protective of her biological mother. Beneath her sullen exterior, she secretly looks to the Kettle sisters for guidance on teenage issues.

Marcus is Gemma's deceased fiancé, who died years ago after being struck by a car. While publicly charming, he secretly exerted extreme control over Gemma and subjected her to verbal and physical abuse, leaving deep psychological scars that dictate her present behavior.

Maddie is Lyn and Michael's two-year-old daughter. She is energetic and prone to public tantrums that deeply embarrass her perfectionist mother.

Hank is an American publisher and Lyn's former flame. He reconnects with her through long-distance correspondence, offering a safe, disconnected outlet for her to confess her hidden anxieties.

Georgina is Michael's ex-wife. She harbors lingering resentment over the end of her marriage and frequently aims snide, undermining remarks at Lyn regarding her parenting skills.

Annie is a relentlessly cheerful therapist attempting to help Cat and Dan repair their marriage. Her chirpy demeanor entirely misses the depth of Cat's anger, and she is easily distracted by the novelty of treating a triplet.

Olivia works as a waitress at the elegant seafood restaurant in Sydney where the triplets celebrate their thirty-fourth birthday. She witnesses the explosive argument that ends with a fondue fork being thrown.