Season synopsis
Contains spoilers for this season and earlier seasons.
Season 12 gives Walden a health scare that makes him want to become a father. When adoption proves difficult for a single man, he proposes that he and Alan marry and present themselves as a couple; they legally wed to satisfy the adoption process. They meet Louis, a six-year-old boy who has been in foster care, and become his foster parents while the adoption process continues. The household shifts from Walden’s dating life to the two men learning to parent, with Alan’s affair with the social worker threatening their cover story.
Once the adoption is finalized, they later sign divorce papers while continuing to raise Louis together. After the divorce, Alan proposes to Lyndsey; by the series finale she is his fiancée, though the relationship remains unsettled. Jake returns from Japan for the closing story, and Walden is dating Louis’s social worker. Meanwhile, Alan discovers that Charlie has millions in unclaimed songwriting royalties, but the brothers never obtained a death certificate, so Rose is summoned to explain what happened.
Rose reveals that after catching Charlie cheating on their honeymoon, she pushed him in front of a train; a goat was hit instead. She brought Charlie back to Los Angeles, kept him chained in her basement for four years, and brainwashed him. He escapes and claims $2.5 million in royalties, sending money to people from his past, including a $250,000 check to Jake. Jake returns, married and living in Japan, and turns the money into a fortune in Las Vegas. Charlie reaches the beach house seeking revenge, but a grand piano crushes him before he can reach Alan, ending with Charlie dead at last.