'A Friend of Joe's' or 'A Friend of Joe'?
If the word "of" shows possession, aren't the apostrophe and S redundant in "a friend of Joe's"? Perhaps, but if you can't use a possessive S and a possessive noun in the same sentence, how do you explain why "a friend of mine" is better than "a friend of me"? Because English isn't precise and isn't even supposed to be. Here's the full story.