Mary Is The Hero
It is Mary who chooses George, not the other way around. In a scene from their childhood, she sits on the counter and whispers in his bad ear, "George Bailey, I'll love you 'til the day I die," while George, oblivious, drones on about coconuts. Reunited at the high school dance, her eyes fix on him with a loving gleam. Throughout their strange, bittersweet courtship, it is she who chases him. George, for his part, is outraged, protesting, ultimately helpless (his boyhood aspirations and college focus fall apart), and gives in.
Mary could marry any man in town. She doesn’t want to. She wants George.
It is Mary who sees the potential of the old house from the first, Mary who acquires it and patiently restores it over the years.
It is Mary who sees the oncoming bank run (wedding day) as well as its solution, Mary who offers up their honeymoon money without wasting time either asking for permission or indulging in regrets. It is Mary who runs around town on her own two legs to fundraise thousands of dollars while George drives away to the bridge and meets the angel of the Christmas future, getting wet, getting drunk, etc.
George’s life is shaped by a recurring characteristic act: the heroic acquiescence to duty when circumstances require it. But Mary sees the greater vision from the start. She is determined that George will lasso the moon, even if she is the only one who can see it in the sky. She is, as much as George, a profoundly unusual person labouring under her own personal destiny. In the world where George does not exist, she has not married not because she couldn't, but because she does not want to. Mary Hatch does not do anything just because it's what might be expected of her.
It is seeing the alternate Mary that breaks George enough to make him ask for life. When he chases the alternate Mary through the streets, his desperate cry is not “Mary! What have they done to you?” but “Don’t you know me? What’s happened to us?” If Mary does not "know" him, if Mary no longer recognizes the man she married, he has failed her, he's no longer the man she thought he was, and that revelation brings him back to his proverbial knees, begging for his life. Alternate Mary not recognizing him is his fear that the real Mary will no longer recognize the man she married if the man she married is facing ruination and disgrace.
But when he gets back, there is no ruin and no disgrace. "Isn't it wonderful?" says Uncle Billy. "Mary did it, George, Mary did it."