It would be foolish, indeed reckless, to read this post without having first read this one.
Listen, you, I have something to say.
The you is dull and voiceless and could be replaced with many other far more fascinating words. For example:
Listen, dude, I have something to say.
The choice of substitute says nothing about the person being addressed, but an awful lot about the speaker or writer. It therefore gives the sentence a distinctive voice. In writing, where you have no accent or body-language to help you along, that is frightfully important. One well placed vocative can set the authorial tone for a whole book, blog post or ransom note.
Dear = married
Darling = Engaged or theatrical/fashion/overbearing female/gay
My child = Biblical and therefore whimsical
My good man = 1950s, Middle Class and slightly enraged
Dear Reader = Austenish
Gentle Reader = Eighteenth Century. It tells you to read the whole work in a particular, mannered way.
Buddy = American
Chuck = Northern working class
Duck = Ditto
Petal = Working class
Guv = Ditto
Babe [to a man or unknown, unisex reader] = California cool?
Poppet = Wonderfully old fashioned and endearing
Old Bean = Bertie Wooster
My Friend = Sinister mafioso
Dude = American, young. Unlike my friend, dude suggests reciprocity and similarity. I cannot call you dude unless I am a dude myself. (I am not a dude).
Love = Unshaven
Cherie, Bella, Liebling etc = Effusive female OR gay man
Sweetness = Camper than a row of tents
Hon (or, if she's German, Hun) = Familiar and vaguely American
Baby = Generally cool
Babe = One should remember David Cameron's "I love you, babe" to his wife "caught" on microphone after his conference speech, and Pamela Anderson's respose in the profound and moving film Barbed Wire, where she shoots people.
Mate = If you are my mate, I am your mate. I am insinuating that I share approximately your views on football, beer and the fairer sex.
Pal = In England always aggressive, but in a weirdly middle-class way
Son = Authoritative, but also threatening
My boy = Healthy, bullish, red-faced
Dear boy = Camp or terribly posh
Chief = Southern working class
Man = This is some good shit we're smoking
Mister = 1930s Chicago Gangster, 1970s cockney, 1990s... in fact there are so many disctinct voices that could be deduced that I should avoid this one until after the voice has been established.
Old chap = Charming in a Terry Thomas sort of way (and if you don't know who that is, click here)
Due to the continuing phallologocentric nature of society (a condition that I do my level best to perpetuate) you can use male vocatives from an unknown reader, but not female ones.
Once, on a train, I was slyly reading a love-letter over the shoulder of the lady next to me, because I am an incorrigible snoop. In it, her beau referred to her as "my little snugglosaurus." There were tears in her eye.
I'm not sure why.
As ever, corrections and additions in the comments please.
Miss Anderson reacting to the Inky Fool's views on vocatives