Tools of Characterization
Characterization in When Harry Met Sally
Dialogue
Harry and Sally quite simply never shut up. Whether they're talking to each other, to their respective besties, or to Ira, pretty much everything you need to know about these two can be sussed out by listening to their dialogue.
For example, we get Sally in a matter of seconds. All it takes is for her to order the chef's salad at a roadside diner and we get the picture: she's controlling and picky.
As for Harry, well, we had his number the minute he said "Look, when the s*** comes down I'm gonna be prepared, and you're not. That's all I'm saying."
Relationships
Harry's divorced. Sally's newly single. And hoo boy did their respective exes do a number on these two. Relationship status also helps define other minor characters. Marie is hopeless in matters of love until she finds wedded bliss with Jess. Alice is happily (though perhaps sexlessly) married, and does her best to help her friends along that path, too.
Names
Sally Albright is all brightness and cheer. She's perky as all get-out, and as Harry points out, nothing bothers her.
And speaking of Harry, his last name is Burns. Harry literally burns with his scathing, sarcastic one-liners. Ah, we see what you did there, Ephron.