After his wife kicks him out, Alan chooses to move in with his brother Charlie.
After 12 years of marriage, Judith kicks Alan out, prompting him to seek help from his older brother, Charlie, and move in with him. But Charlie struggles to adjust his laid-back lifestyle to make room for Alan’s ten-year-old son, Jake.
Alan disciplines Jake for something that happened at Judith’s house, but Charlie is too relaxed about enforcing rules. When Jake’s actions lead to a flock of seagulls invading Charlie’s home, Charlie realizes he needs to start setting boundaries with his nephew.
Charlie and Alan go out for drinks, and Alan attempts to reconcile with his wife. When that doesn't work, the brothers decide to face the real source of their issues—their mother.
Charlie’s housekeeper, Berta, quits due to Alan’s behavior, but Charlie soon realizes he can’t manage without her. Meanwhile, Rose asks for Charlie’s help getting ready for a date.
After a wild night in Las Vegas, Charlie reluctantly agrees to attend one of Jake’s football games. However, he and Alan quickly realize the unexpected benefit, meeting and dating the players' very attractive mothers.
Charlie begins to rethink his behavior toward women when he, Alan, and Jake have to comfort their mother, Evelyn, after her breakup. Meanwhile, Charlie gives Jake some unconventional advice on how to screen phone calls.
Jake spots a butterfly tattoo on the lower back of one of Charlie’s friends and uses her as inspiration for a school art project. This upsets his mother, Judith, though she later ends up becoming good friends with the woman.
Judith manipulates Charlie into helping with Jake’s school musical, while Alan is caught off guard by receiving divorce papers, straining his relationship with Judith. Meanwhile, Jake feels let down as he realizes his parents are unlikely to get back together.
Charlie looks for a way to break up with his new girlfriend, whom Jake has grown to love and who has also bonded with Evelyn, making Charlie fear she wants something more serious. Meanwhile, Alan and Rose grow closer over a game of Scrabble.
When Charlie’s favorite ex-girlfriend announces her engagement, he attempts to win her back, leading to rising tensions and conflicts during the family’s Thanksgiving gathering.
After encountering his ex-wife and her new boyfriend, Alan realizes he needs a makeover to re-enter the dating scene. However, when he goes shopping with Charlie, the two clash over what to buy.
Berta brings her 16-year-old granddaughter to work, catching the eye of both Charlie and Alan and stirring up trouble. Meanwhile, Alan tries to persuade Judith that Charlie’s home is the right place for Jake.
Charlie takes care of Alan as he recovers from a contagious flu, hoping to convince him to join a double date, despite Alan’s strong reluctance.
When Charlie finds out his credit rating is ruined and his debts are overdue, he realizes his accountant has been utterly incompetent. Meanwhile, the accountant struggles to make Charlie grasp the seriousness of his financial troubles.
Even though Alan warns him, Charlie falls for a wild woman named Frankie, whom he meets in the garage, leading to a series of unusual and thrilling adventures between them.
After Frankie convinces Charlie and Alan to let her and her eight-year-old daughter, Joanie, stay with them, she opens up about why they fled. Charlie wants them gone, but Alan insists they remain, and Joanie quickly bonds with Jake.
Charlie takes offense when Alan names his married, responsible cousins as Jake’s guardians in the event of his death, despite their lack of intelligence.
Charlie agrees to meet his ex-girlfriend, who ended their relationship years ago, leaving him heartbroken. However, he’s in for a shock when he learns she has transitioned to a man. Shortly after, Evelyn meets him and they start dating.
Judith’s sister, Liz, shows up for Jake’s eleventh birthday party, sparking a series of unexpected events with her mix of charm and mischief.
Jake starts behaving oddly and shuts down communication, prompting Alan and Judith to send him to a therapist after realizing he’s struggling to cope with their divorce.
Fearing Jake’s custody could be at risk, Charlie tries to charm Alan’s divorce lawyer. They keep this from Alan, viewing Charlie as part of the team, but the situation ends up threatening Alan’s divorce settlement.
While Charlie works on helping Alan overcome his recent, ongoing sleepwalking, Jake starts therapy sessions.
Charlie attempts to persuade Judith to keep allowing Jake to stay at his place on weekends, but meets opposition from her and her friends, leaving him responsible for smoothing things over.
After a year of raising Jake, Charlie feels he's not ready for fatherhood and decides to get a vasectomy, as long as it doesn't affect his vital organs, both physically and metaphorically.