Walden decides to foster a six-year-old named Louis.

Alan breaks Walden's rules to appear cool for Louis.

Charlie finds himself in a relationship that is not based on sex.

Charlie arranges a romantic date with Mia in the hopes of consummating their relationship whilst Alan begins to date Charlie's most recent ex-girlfriend.

Charlie has trouble keeping up with Mia's healthy lifestyle, so he begins to sneak beers, cigars and burgers behind her back. When Mia finds out, Charlie has to decide if he is truly in love with her or just whipped.

When Raj is cut off from his father's fortune, he appoints Sheldon in charge of his finances to help him get out of debt. Meanwhile, Penny considers joining Leonard at Comic-Con.

When Raj moves out of his apartment, Leonard and Penny offer him Sheldon's old room. Christine Baranski returns as Leonard's mother, Beverly.

Leonard, Penny and Raj adjust to their new living arrangement, while Sheldon takes an interest in Amy's work.

Joey's agent dies but the gang don't want to tell him since his life has been changing so much lately. Janice is bidding on the house next door to Chandler and Monica and Ross is trying to get Rachel her old job back.

The gang throw Rachel a going away party and she says goodbye to each of her friends individually. Meanwhile, Erica is in town until the baby arrives and ends up going into labour at the party.

Ross has a hard time dealing with Rachel's decision to move to Paris whilst Phoebe and Joey pack Monica and Chandler's belongings as the couple accompany Erica, who has gone into labour, to the hospital.

Ross and Phoebe race to the airport to tell Rachel of his feelings. Erica gives birth to twins Jack and Erica and the friends turn in their apartment keys and go out together for one last coffee at Central Perk.

Charlie finds himself in a relationship that is not based on sex.

Charlie arranges a romantic date with Mia in the hopes of consummating their relationship whilst Alan begins to date Charlie's most recent ex-girlfriend.

Charlie has trouble keeping up with Mia's healthy lifestyle, so he begins to sneak beers, cigars and burgers behind her back. When Mia finds out, Charlie has to decide if he is truly in love with her or just whipped.

When Raj is cut off from his father's fortune, he appoints Sheldon in charge of his finances to help him get out of debt. Meanwhile, Penny considers joining Leonard at Comic-Con.

When Raj moves out of his apartment, Leonard and Penny offer him Sheldon's old room. Christine Baranski returns as Leonard's mother, Beverly.

Leonard, Penny and Raj adjust to their new living arrangement, while Sheldon takes an interest in Amy's work.

Joey's agent dies but the gang don't want to tell him since his life has been changing so much lately. Janice is bidding on the house next door to Chandler and Monica and Ross is trying to get Rachel her old job back.

The gang throw Rachel a going away party and she says goodbye to each of her friends individually. Meanwhile, Erica is in town until the baby arrives and ends up going into labour at the party.

Ross and Phoebe race to the airport to tell Rachel of his feelings. Erica gives birth to twins Jack and Erica and the friends turn in their apartment keys and go out together for one last coffee at Central Perk.

Alan has trouble deciding if he should bring his younger girlfriend to Jake's birthday party to meet his mum and his ex-wife. Rose tries to get her boyfriend to act more like Charlie.

Charlie is nominated for an advertising award but decides to boycott it because his arch nemesis always wins. Rose is having relationship problems with Gordon and seeks help from Charlie.

Alan starts to have financial problems when he starts paying for his girlfriend's bills, so Charlie tries to get him to break up with her. Meanwhile, Judith is after Alan because he's late in paying his alimony check.

Sheldon pushes himself to the limit when he collaborates on projects with Leonard and Howard as well as Amy on the same day. Meanwhile, Bernadette nears the end of her maternity leave.

Howard and Bernadette have a hard time leaving Halley in daycare when Bernadette returns to work. Meanwhile, Bert introduces the gang to his new girlfriend, Rebecca.

Leonard isn't thrilled when Penny considers taking a new job offered by her ex-boyfriend, Zack.

This is the one where it all began... Rachel leaves Barry at the altar, meets the gang, and moves in with Monica. Ross is reeling from his divorce from Carol who has become a lesbian.

Ross's lesbian ex-wife tells him at work that she is pregnant with his child and that her and Susan are planning to bring up the child. Rachel finds out that Barry and her maid of honour, Mindy, went on her honeymoon.

Everyone likes Monica's new boyfriend way more than she does. Phoebe discovers a human thumb floating in a can of soda & gets seven thousand dollars compensation, which she offers to Chandler to quit smoking.

Ross mourns the anniversary of losing his virginity to Carol. Rachel gets her first pay cheque but is angry most of her money went to FICA. The girls spy on the sexy politician across the street, George Stephanopoulos.

Walden's attracted to a mom at the kids' gym.

Walden and Alan try to convince Louis that Santa's real.