Summary

• Leslie Mann and Paul Rudd return as the focus of This Is 40 shifts onto their marital struggles.
• A new version of Jason Segel's character returns in This Is 40.
• Alison and Ben are the two biggest characters from Knocked Up that don't appear in the sequel.

This Is 40 sees the return of characters from the 2007 comedy, Knocked Up. Both films are directed and written by Judd Apatow and feature comparable storylines. Knocked Up was largely focused on Alison (Katherine Heigl) and Ben (Seth Rogen) as they navigate life as soon-to-be parents, despite their ill-timed circumstances. Knocked Up also stars Leslie Mann as Alison's sister, Debbie, and Paul Rudd as her husband, Pete. The latter couple have relationship issues of their own, but spend most of their time helping out Alison and Ben. This Is 40 changes this and catches up with Debbie and Pete five years later.

Both films share similar themes that showcase the unpredictability of romantic relationships and family life. Many of the main characters from Knocked Up return in This Is 40, such as the children of Debbie and Pete, but other characters, most notably Ben and Alison, are absent from the sequel. Judd Apatow has addressed this inconsistency in This Is 40, saying he didn't feel the need to introduce an older Ben and Alison because, in many ways, that's what the marriage between Debbie and Pete represents.

7 Jodi

Played by Charlyne Yi

Knocked Up features a group of individuals living together while working to set up their website. Among the group is Charlyne Yi’s Jodi, who is first introduced when Alison comes by the house for the first time. Jodi is under the influence at this time and, as a result, she's known for her odd commentary. Yi's minimal appearance is the extent of her part in Knocked Up, yet she returned to portray Jodi once more in This Is 40. Five years after the events of Knocked Up, Debbie owns a boutique and Jodi is an employee.

None of Jodi's dialogue mentions her roommates from Knocked Up, but in a humorous confrontation between Jodi and Debbie, audiences learn the character still uses drugs. Debbie discovers Jodi stole money from the company and while firing her, she mentions a previous time when Jodi babysat Debbie's children while under the influence of drugs. Jodi appears to be unbothered by her actions and, due to her odd behavior, it's assumed she's high during their conversation. This is the last time Yi is on-screen and while her part in This Is 40 is still minor, Jodi's character played a large part in Debbie's troubles.

6 Dr. Pellagrino

Played by Tim Bagle

Just like her sister, Debbie did not plan her pregnancy and her reaction is reminiscent of Alison's.

As Dr. Pellagrino, Tim Bagley returns to This Is 40 and delivers the same news to Debbie as he previously shared with her sister Alison. In Knocked Up, Dr. Pellagrino confirms to an unsure Alison that she is indeed pregnant. Upon receiving the news, Alison breaks down into tears, overwhelmed with panic. Similarly, Dr. Pellagrino tells Debbie she is pregnant. Just like her sister, Debbie did not plan her pregnancy and her reaction is reminiscent of Alison's.

Bagley's role is minor, and ultimately Debbie's pregnancy does not take up as much of the plot as Alison's. Debbie is struck with panic and stress due to her financial and marital complications with Pete, but spends the majority of This Is 40 keeping the news to herself. Pete only finds out in the film's third act and audiences don't see what happens to the couple once the baby is born. Dr. Pellagrino's dialogue had a greater impact on Alison's life than it did Debbie's, but his return in This Is 40 adds to the film's overall continuity from Knocked Up and it's comical for audiences to see the sister's nearly identical reactions.

5 Jason

Played by Jason Segel

Ben's group of friends in Knocked Up consists of characters played by Martin Starr, Jonah Hill, Jason Segel, and Jay Baruchel. Each actor has appeared in other Apatow productions, but only Segel returned in This Is 40 as his character Jason. The version of Jason in Knocked Up spent most of his days at home and smoking marijuana. Additionally, Jason helps out with the group of guys and takes the time to log the timestamps of particular movie scenes, as they're setting up an adult website. This Is 40 shows a version of Jason that's almost unrecognizable.

Jason now works as Debbie's trainer (or as he views himself, her "spiritual guide"). During a workout session early on in This Is 40, Jason encourages Debbie's pursuit of fitness and lends a friendly ear as she vents to him about her marital strains. Keeping in line with his actions from the first film, Jason tends to subtly flirt with Debbie. However, the two don't discuss the previous years of their connection or their relationship with Ben and Alison. Jason doesn't appear in any other setting in the film, other than when he attends Pete's 40th birthday party and competes with another man for a woman's attention.

4 Sadie

Played by Maude Apatow

Judd Apatow's daughters star in his projects quite often, and they both return as their characters, Sadie and Charlotte, in This Is 40. Throughout much of her dialogue, Sadie (Maude Apatow) has a distinct sense of humor. One of Knocked Up's most memorable scenes is when Sadie explains her understanding of having a baby to the adults at the table. Sadie's explanation is the best representation of Apatow's young talent, as it's equally hilarious and adorable. Sadie and her sister Charlotte don't take up much time in Knocked Out, but their scenes perfectly set up the growth of their characters in the sequel.

She enjoys spending her time binge-watching the entirety of Lost and chatting with her friends on social media

Sadie is 13 years old by the time This Is 40 takes place and her teenage view of the world adds additional stress to an already tense period for Debbie and Pete. Debbie decides to change the family's lifestyle, which includes minimized screen time, but Sadie struggles the most with this change. She enjoys spending her time binge-watching the entirety of Lost and chatting with her friends on social media. The latter gets herself and her parents in trouble with another teenager at school and results in one of the film's more memorable scenes when Debbie and Pete confront the teenager's mom, Catherine, humorously played by Melissa McCarthy.

3 Charlotte

Played by Iris Apatow