Après l'échec de leur mariage, Oscar et son ancien colocataire d'université, Felix, décident de vivre ensemble.

Felix propose son aide lorsqu'Oscar est engagé pour écrire l'autobiographie d'un joueur de baseball à la retraite.

Quand Oscar se rend compte qu'il a oublié l'anniversaire de Félix, il organise une fête surprise impromptue.

Dani souhaite avoir un petit ami pour sa réunion de lycée alors Oscar, Felix et Ted travaillent à lui trouver un homme.

Quand Oscar et Félix assistent au mariage d'un vieil ami d'université, Oscar vise à renouer avec une ancienne flamme tandis que Félix est déterminé à montrer à son ex-femme qu'il est un homme changé.

L'hypocondrie de Félix s'emballe lorsqu'Oscar commence à sortir avec la personne la plus importante de la vie de Félix, son médecin.

Felix convainc Oscar d'apparaître dans une émission de télévision sportive contre le conseil de Teddy de rester à la radio.

Quand Oscar se sent menacé par la surprenante performance de Félix sur le terrain de softball et de basket, ils s'accordent pour un décathlon afin de déterminer lequel d'entre eux est le meilleur athlète.

Quand Oscar et Felix se rendent chez Ashley pour récupérer l'oreiller spécial de Felix, un secret qu'il a caché à Oscar est révélé.

Lorsque Félix remplace enseigne un cours de yoga, son style d'enseignement frotte tout le monde, y compris Emily, dans le mauvais sens. De plus, Oscar et Dani se retrouvent piégés dans une voiture de métro, ce qui ajoute à leur frustration de vivre dans la ville, et Murph demande à Teddy d'être son agent lorsqu'il est approché pour être le porte-parole d'un supplément de santé norvégien.

Oscar devient étrangement obsédé par la réputation de Murph lorsqu'il découvre que la fille qu'il voit avait l'habitude de sortir avec le bel ex-joueur de baseball.

Lorsque l'IRS décide d'auditer Oscar et son ex-femme, Gaby, Felix propose de servir de médiateur entre les ex litigieux et se rend compte soudainement qu'il pourrait être la raison pour laquelle Oscar a été audité en premier lieu.

After Oscar and Felix become obsessed with eavesdropping on their bickering neighbors, they try to subtly intervene and help them save their marriage. Meanwhile, Emily and Dani's friendship is tested when they train together to race to the top of the Empire State Building.

With the help of Murph, Oscar decides to throw a big party when Felix finally agrees to spend the weekend away. Also, Felix and Emily have their first sleepover.

Oscar faces a personal dilemma when he dates a young nanny, Allyson, who works for his neighbor, Charlotte. Also, Emily forces Felix to participate in an activity she's interested in, for a change.

Oscar's dream comes true when he is asked to throw out the first pitch at a New York Mets game. Also, Felix surprises Oscar and invites his father to be there for the big day.

Oscar attempts to impress Charlotte by purchasing a table for a fundraiser to benefit The New York Philharmonic. At the event, Felix reminds Oscar about the importance of being honest and Teddy introduces his wife, Diane, to Dani for the first time.

Oscar and Charlotte hit a speed bump when they hesitate to take their relationship to the next level. Also, Felix attempts to overcome his fear of dogs with Teddy's help when Emily regains custody of Biscuit.

Oscar reluctantly agrees with his agent that it’s time to shake things up on his radio show and allows Dani to have a bigger role after a rival host, Rich Eisen, taunts him. Also, Felix is eager to meet Emily’s mother, Judy (Joanna Cassidy), but things don’t go as well as he hoped.

Felix attempts to reverse Emily's birthday curse and plans a nice dinner to celebrate with friends. Also, Oscar and Charlotte face another obstacle in their relationship when Oscar meets Charlotte's son, Evan (Caleb Brown).

Oscar learns that Felix was nationally ranked chess player as a child and convinces him to return to the game to make money. Also, Emily investigates why Felix is acting strange since he began playing chess again,

Felix forces Oscar and Emily to go on a date to get to know each other better in the hope that they’ll become friends. Also, Teddy agrees to help Dani with her first contract negotiation.

In an attempt to surprise Emily, Felix gets his learner’s permit and enlists his friends to help him learn how to drive. Also, Oscar is annoyed that Felix doesn’t ask him for help,

Oscar and Felix run a heated campaign for president of their building’s tenants’ association, but Oscar doesn’t fully realize everything the position entails.

After Murph persuades Oscar to try online dating, Oscar finds himself on a blind date with Felix’s ex-wife, Ashley.

Oscar is forced to choose between his romantic plans with Charlotte and helping to save Felix’s relationship as Emily decides to extend her stay in London and Felix starts to fall apart.

When Oscar learns that his favorite hangout, Langford’s, is in financial trouble, he impulsively asks Felix to help save it, without considering the disastrous consequences. Also, Felix tries to make his mark on the restaurant when the owner, Fred Langford , puts him in charge for a few days.

Oscar sets out to prove to Charlotte how he's capable of being responsible when he volunteers to take her son Evan (Caleb Brown) trick-or-treating on Halloween, while Felix celebrates the holiday by leading the kids in their building on a haunted history tour.

Oscar reconnects with many significant people from his father's life when he agrees to carry out Walter's last request to spread his ashes behind the candy factory he once owned.

Dani's excitement at being promoted is cut short when Oscar tasks her with the daunting job of hiring her own replacement. Also, Felix tries to plan the perfect surprise after Emily admits she misses England.

After his arch enemy Rich Eisen receives a humanitarian award, Oscar is forced to give a speech and wants to roast him. Meanwhile, Felix tries to fast-forward through the five stages of grief following his breakup with Emily.

Things get out of hand when Felix begins to meddle in his friends' personal lives and hires a counselor to help resolve their issues. Among the problems: Teddy's wife Diane believes that he is cheating on her with Dani after he stays out all night and Dani's moving in with Emily has created friction over the way the apartment is decorated.

Felix goes into a frenzy when the responsibility of hosting the Unger family Christmas falls onto his plate after his perfectionist mother bows out. Meanwhile, Oscar tries to convince his roomie's mom to give her son a break.

Oscar arranges for Felix to replace him on any cultural outing that Charlotte has planned; and Emily recruits Dani, Teddy and Murph for help making 100 necklaces for an event.

Felix takes the first step in moving on from Emily by picking up a bartender named Natasha (Busy Philipps) and bringing her home for the night. It later backfires when Felix doesn't know how to have a one-night stand; Natasha starts to get attached and won't leave. Meanwhile, Oscar takes his relationship with Charlotte to the next level by asking her to leave her toothbrush at his apartment, after which they get into a conversation about their relationship and say "I love you" to each other.

Murph is hosting a new TV sports segment wherein Oscar is pitted against a penguin to pick the winners of hockey games. Oscar soon becomes the butt of jokes when the penguin's random picks (made by walking under one team logo or another) turn out to be more reliable than his. Elsewhere, Emily asks Felix to shoot photos of her for a jewelry website, but Felix misinterprets her verbal cues and thinks she wants to get back together with him.

Oscar grumbles when Felix helps Dani prepare for a choir solo and encourages the group to attend church to support her.

After a heated argument, Oscar and Felix decide it might be best to change their living arrangements and find new roommates.