Two and a Half Men (season 12)

Walden, dressed as Zombie Elvis, and Alan, dressed as Duckie from Pretty in Pink (a role Cryer actually played) but mistaken for Ferris Bueller, are preparing for a Halloween party when Walden suffers a mild heart attack. Alan and Berta both sit in the hospital waiting room and worry about their friend. Though the doctor says he should make a full recovery, Walden begins to rethink his life and decides he wants a child. He visits an adoption lawyer (Aisha Tyler), who tells him the system is rigged against single males adopting children. Having one failed marriage and two other women in his past who fled after he proposed, Walden is at an impasse, so he proposes to Alan.

After thinking about the proposal, Alan agrees to marry Walden. According to Walden, Alan has 9 out of the 10 things he wants in a spouse. They break the news to their mothers, Berta, and Jenny, who are all shocked by their announcement.

As Alan is planning his perfect wedding, Walden nixes the elaborate ceremony and honeymoon plans. Walden explains that they have a "business deal" and the wedding will be in a courthouse. Walden then brings Alan a pre-nuptial agreement to sign. Alan is hurt that Walden doesn't trust him, and runs off in tears. Evelyn tells Alan to not sign anything, saying she didn't sign anything when she recently married Marty Pepper. Walden's mother Robin tries to set him up with either her female or male assistant. Alan returns home and they apologize to each other. Alan signs the document, agreeing that Walden is the only one with assets worth protecting, and they confirm to each other that they are best friends.

To give Alan a memorable wedding, although it is with a judge, Walden gets Michael Bolton to sing. Walden surprises Alan with prepared vows and even kisses him after they are proclaimed married. Later, following a night of wild partying, Robin and Evelyn sneak out of the house after participating in a threesome with Bolton.

Walden and Alan are scheduled to meet with social worker Ms. McMartin (Maggie Lawson) about adopting a child. Jenny says they will really have to "sell" their being a gay couple. She decides to move in with Evelyn while Walden and Alan prepare for adoption. When Ms. McMartin says she wants to visit the home, Walden and Alan "practice" being gay. Lyndsey complicates things when she returns after spending 60 days in rehab, and says she wants to get back together with Alan. Alan breaks the news that he is now married to Walden. On the day Ms. McMartin arrives and is in the kitchen discussing things, a now-drunk Lyndsey arrives at the door, saying that if Alan only married Walden to help him get a child, she and Alan can still have sex on the side. Alan quickly hides her in his bedroom where she passes out. She is later seen on the deck in just her bra as Walden and Alan try to distract Ms. McMartin. McMartin finally sees Lyndsey at the front door, but Jenny saves the day by pretending she is a neighbor and Lyndsey is her drunk friend. Later, Walden happily breaks the news to Alan that they have been approved to adopt.

After Walden baby-proofs the house and it passes Ms. McMartin's inspection, she says there is a pregnant college student named Kathy who wants to give up her baby. Kathy meets Walden and Alan and feels they are the perfect couple to raise her child. Herb, Barry, and Larry join Walden and Alan to celebrate. A confused Larry somehow thinks Alan and Walden are having their own child. All the men go to the hospital to see the newborn. Walden gets to hold the baby boy, shortly before Kathy says she's changed her mind and wants to keep him.

Ms. McMartin asks Walden and Alan if they would consider adopting a 6-year-old boy named Louis, and sets up a six-month trial after they accept. Walden tries very hard to make Louis feel at home, but the two don't get along as well as he hoped. After talking with Berta, who was also a foster child, Louis later climbs into Walden's bed and asks if Walden will make him leave after the weekend, as has happened to Louis many times before. Walden assures Louis that he can stay as long as he wants. Louis then wonders aloud why Alan is not in bed with Walden.

First appearance of: Louis

Ms. McMartin approves Alan and Walden to foster Louis for six months with a view to adopting him. She warns that Louis, being a foster child that has moved around a lot, may have some behavioral problems. Sure enough, Louis tries to manipulate Alan to get what he wants, which causes Alan and Walden to clash when Alan breaks Walden's rules in order to be the "cool" dad. After Louis continues to try to get what he wants by refusing to put a box of cereal back at the grocery store, Walden has Alan use some of his previous expertise with Jake to fix the situation. Both Alan and Walden keep the cereal for themselves in the end.

While Walden and Alan are both enjoying being parents to Louis, they're also increasingly exhausted by the little dynamo and take him to an indoor play center hoping he'll give them downtime while he plays with other kids. Alan ends up meeting a trio of attractive moms and they bring their kids to the beach house to hang out. Alan plays the married gay man to the hilt and ends up having a wild night out with two of the women, while Walden stays home to look after a sick Louis and is surprised when the other mom, Laurel, comes over. He tells her the truth about him and Alan and she seems to accept it; they nearly have sex, but Walden goes to look after Louis and ends up falling asleep next to him.

It is Christmas time and Rose comes over and offers her help, but is turned down. Louis does not believe in Santa as he never got presents, so Walden and Alan want to prove him Santa exists by hiring a Santa who will be captured on video. Unfortunately, while Alan and Walden are in the garage putting together Louis' new bike, sex between Evelyn and the fake Santa leads to a trip to the emergency room for the latter. Sometime later, Louis can't sleep, and asks Walden and Alan to stay with him; the two wind up falling asleep. In the morning, however, they discover all the presents under the tree and a video of Santa. Walden realizes Rose was responsible when he sees "Santa" leaping over the balcony railing. Rose tells Walden she really does want to be friends with him, and surprises Walden with a Christmas gift – a cuckoo clock (that, unknown to Walden and Alan, is actually a spy cam).

Laurel brings her daughter to the beach house for a play date with Louis. After the kids fall asleep, she and Walden attempt to have sex, but Louis interrupts. They later decide to get a hotel room while babysitters watch the kids. Just as they are getting intimate, Laurel hints that Louis has trouble sharing while Walden retorts that Laurel's daughter is a biter. The two argue, then have angry sex. Meanwhile, Herb has just completed Alan's physical exam, and says Alan really needs to exercise more. He suggests Alan come to his yoga class, which has the added benefit of being surrounded by hot women. One of the "hot women" they see there turns out to be Lyndsey. After Alan and Lyndsey argue a bit, Herb asks if he can pursue Lyndsey, given that the she and Alan are no longer together. Despite agreeing it would be a bad idea and a violation of the "bro code", Alan finds that Herb did indeed sleep with Lyndsey when he goes to apologize to her later.

During a surprise check up, Ms. McMartin sees a half-dressed Laurel emerge from Walden's room, and is angered to discover that he and Alan were pretending to be a gay couple. She plans to remove Louis from the house. In a desperate attempt to change her mind, Alan tries to reason with her, which leads to them having sex and the social worker complaining about her life and occupation. Walden becomes devastated over losing Louis and eventually has to say good-bye when Ms. McMartin comes to pick him up. However, she changes her mind at the last minute upon seeing how happy Louis is with them, and agrees to let him stay as long as Alan and Walden tell her no more lies, unless her boss asks about them. She and Alan end up in bed again, with Alan asking her what her first name is.

Alan sleeps with Ms. McMartin again, and tells Walden about it the next morning. Walden is furious, thinking their relationship might jeopardize the adoption of Louis, which is still pending. Walden joins a support group of adoptive fathers so that he can discuss his concerns. He and the group's four members hit it off, and Walden is happy to have friends other than Alan to talk with. When the group meets at the beach house, Walden hurts Alan's feelings by telling him he'd prefer to have Alan leave for the day rather than join the group. When Alan invites himself to join, however, Walden gets annoyed when the group takes a liking to Alan.

Lyndsey, returning some of Alan's things, announces she is moving away for a fresh start. After sleeping together, Alan asks her to get back together and she says she will think about it. Walden is worried since Alan is also sleeping with Ms. McMartin. While Alan and Ms. McMartin are dining, Lyndsey shows up, furious that Alan didn't tell her he was seeing someone else. Ms. McMartin, also furious with Alan, shows up in the middle of the night for a surprise inspection of the beach house. Walden goes to talk to the distressed Ms. McMartin, but he ends up sleeping with her and she becomes convinced that they have started a relationship. Alan seems to have won Lyndsey back after showing up at her house holding up a boom-box.

After Alan and Lyndsey reconcile, she starts looking for an apartment and then asks Alan to move in with her. No apartment is good enough for Alan who then admits that his perfect place is Walden's beach house. Lyndsey leaves after he chooses the beach house over her. Walden breaks up mutually with Ms. McMartin and then officially adopts Louis. Realizing that the two of them are going to end up alone together and that their women are perfect for them, Alan goes running after Lyndsey at the airport and Walden asks Ms. McMartin for another chance. She agrees after being serenaded by Michael Bolton. Alan ends up being hit by a taser by a TSA guard as he tells Lyndsey that he loves her.

As both couples are getting along together, Walden decides he wants to get divorced from Alan and move on. Walden gives Alan a wish because he was such a good friend in helping him adopt Louis. Alan gets a Ferrari, which makes Lindsey mad, as both she and Walden think Alan should have wished for something that included Lyndsey. Alan decides to propose to Lindsey — especially after Walden offers to buy the engagement ring. Walden in turn offers nothing but support, but then panics that he might truly end up alone if he lets Alan move out so he frantically begs Alan to stay at the beach house forever. Alan, surprisingly, declines but assures Walden that they will always be friends and he'd still come to visit. Lastly, Alan finally proposes and Lyndsey at first balks, but she happily says yes upon seeing the huge diamond in the ring.

Alan tries to prove Charlie is dead in order to collect $2.5 million in back-royalties, but has no proof other than Rose's word. Evidence begins to mount that Charlie is still alive. The royalty money is claimed, threatening notes are received, and Jenny, Jake, Chelsea and friends of Charlie receive mysterious checks for large cash amounts along with written apologies. Alan receives a FedEx package addressed to Charlie containing whiskey, cigars, and a knife with which Charlie used to chase Alan.

Rose says that Charlie is still alive, explaining how, after catching him cheating, a goat saved Charlie when Rose threw him into the path of an oncoming train, following which Charlie is returned to America and held captive. Evelyn and Rose then go into hiding while Alan and Walden go to the police before finding the house vandalized with more threats. Jake Harper drops by and tells a surprised Alan and Walden that he left the Army, is now married and living in Japan and has turned his $250,000 into $2.5 million in Vegas. The police say they have captured Charlie, but the suspect is Christian Slater. Alan, Walden and Berta relax in lounge chairs while they smoke Charlie's cigars and drink his whiskey. They observe a helicopter carrying a piano approaching the house. Charlie, seen only from the back, approaches the front door and the piano falls on him. The camera pulls back from the set to where producer Chuck Lorre is sitting, upon which Lorre turns around and says "winning", only to have a piano fall on him.