Charlie Harper is alive. Or is he?

Charlie Harper is alive. Or is he?

After a health scare on Halloween, Walden decides he needs to change his life.

Alan has second thoughts about getting married after he's asked to sign a pre-nup.

Walden becomes a foster parent to a 6-year-old boy, but worries about himself when they don't hit it off like he hoped.

Walden deals with his ex-wife, Bridget.

Alan prepares Walden for a date with Bridget, while Jake decides to emulate Walden and drop out of school.

Alan breaks Walden's rules when he realizes that Louis thinks he's cool, and he wants it to stay that way.

Alan and Walden have a meeting with an adoption social worker that hinges on them being convincing as a loving couple. Lyndsey returns after 60 days in rehab.

Alan and Jake meet Walden Schmidt, a broken-hearted billionaire.

Walden and Zoey's relationship suffers after they share a near-death experience. Meanwhile, Alan wonders if Lyndsey has a drinking problem.

A birth mother considers having Walden and Alan adopt her baby.

Alan and Walden attempt to convince Louis that Santa Claus is real.

Walden joins a group for adoptive fathers, and finds it to be a nice escape from Alan.

Walden goes looking for Mrs. Right while Alan has an opportunity to reconcile with Lyndsey.

Walden receives divorce papers from Bridget, but forgets his depression when he meets a girl who looks eerily like her.

Walden's ex-business partner shows up at the beach house looking to make peace.

Alan and Walden go to Kate's fashion show in New York so Walden can reveal the truth about his identity.

After they sign their divorce papers, Walden offers Alan the gift of his choice, but when Alan chooses something selfish and impractical, it puts his relationship with Lyndsey on the line.

Walden's mother arrives and Alan is smitten with her, even as she reveals a secret about Walden's past that sends him into a downward spiral.

Alan is showered with love and affection upon returning from the hospital, but Zoey isn’t so sure it’s deserved.

Walden fears if he breaks up with Ms. McMartin, it will jeopardize his adoption of Louis. Also, Alan hesitates when Lyndsey asks him to move in with her.

Alan has trouble accepting Lyndsey's seedy movie past, and Walden tries to cheer him up by throwing a party.

Walden discovers how challenging it is to be intimate with women when his foster son, Louis, is in the house. Also, Herb asks Alan if he can go on a date with Lyndsey.

Alan takes it upon himself to help Walden keep Louis after the social worker discovers he and Walden are not really a gay couple.