Tools of Characterization
Characterization in Annie Hall
Direct Characterization
Alvy consistently breaks the fourth wall and addresses the audience directly. In fact, the entire movie starts with him speaking to the audience one-on-one.
In the very first scene, Alvy explains his feelings about life and how it's divided between the terrible and the miserable, setting the stage for Alvy's story to come. Whether he's probing the audience about what to do with an annoying person in a movie line or asking us to forgive him for re-writing the ending of his play about his and Annie's affair, all of Alvy's asides give you the feeling that the dude lives to talk, and talks to live.
Sex and Love
It would be pretty tough to have a romantic comedy where the leads aren't characterized by their thoughts on sex and love, wouldn't it? For Annie, sex is a source of anxiety, as evidenced by her reliance on marijuana.
For Alvy, on the other hand, sex and love are tightly linked. It's little surprise that their different ideas about the bedroom put Empire State Building-sized stress on their relationship. Take the split-screen where they visit their therapists, for example. While Alvy and Annie both agree that they have sex three times a week, Alvy doesn't think that's enough, and Annie thinks it's too much.
Alvy's also strongly characterized by his thoughts on love. In fact, they're the catalyst for the whole movie. Annie Hall is the story of Alvy not only trying to figure out why he and Annie broke up, but also trying to wrap his head around the idea of love, period. (Or, as Alvy puts it to Annie, "loaf" or "luff.")
Alvy divulges at the start of the film:
ALVY: I would never want to belong to any club that would have someone like me as a member. That's the key joked of my adult life, in terms of my relationships with women.
Alvy's on a quest to figure out how love works, and his mission influences his thoughts, actions, and fantasies.
Occupation
All of the main characters in Annie Hall are entertainers by trade. Alvy is a stand-up comedian who unleashes his neuroses on stage before a cackling live audience. Annie is a singer who grows in confidence and skill as the story scoots along. And Rob? He's an actor. Alvy references Rob's illustrious past performing Shakespeare in the Park (and getting mugged), and Rob ultimately heads out west to Hollywood to star in a sitcom.
But Alvy, Annie, and Rob just don't perform on stage. In fact, they're constantly performing. Take Alvy, for example. Even in his misanthropy, he's a quip machine, always quick with a joke. Annie's confidence in her relationship with Alvy grows just as her on-stage poise does, and, ultimately, she outgrows Alvy himself.
Even Rob is perpetually performing. When Alvy visits him in Los Angeles, Rob dutifully—and often ridiculously—acts the part of a superficial, appearance-obsessed SoCal celeb. For Alvy, Annie, and Rob, their characters are inextricably linked to their entertainment gigs. If all three of them were in another industry—tollbooth operators, for example—Annie Hall would be a totally different tale.
Thoughts and Opinions
Alvy is a dude with a lot of opinions, and he's not afraid to share them. He thinks he and Annie should pause their first date to have their first kiss in the middle of the street to "get it over with." Ah, romance.
He tells Annie that relationships are like sharks that have to keep moving or they'll die. He thinks she should keep her own apartment so they don't feel like they're married. He concludes the movie by sharing his hypothesis that love is absurd, but we're willing to put ourselves through all of the nonsense because, ultimately, we need it.
Obviously, this is an incomplete list of the Thoughts and Opinions of Alvy Singer. His feelings about Los Angeles alone could fill a library. But through his thoughts and opinions, we get sharp insight into Alvy's inquisitive, analytic, and thoroughly neurotic character.