I don't know when they became friends. I don't think it was stated. But I don't remember Anne mentioning him as a friend of Wentworth's before she met him.
Last Read: The Ocean at the End of the Lane by Neil Gaiman
Currently Reading: Inferno by Dan Brown
TBR (tentative): Passion of the Purple Plumeria by Lauren Willig
RBC: Farewell to Arms by Ernest Hemingway
I just finished Persuasion so I thought I'd add my thoughts on to the end of this discussion:
I think of the Austen novels I've read so far (Mansfield Park, Emma, Northanger Abbey) Anne is my favourite heroine. She's mature, reserved but not to the point of being at all pathetic and not at all flighty. Her main fault of being too easily persuaded against Captain Wentworth is a very forgivable one, even in the throws of young love I think it's very understandable to be unsure if you're making the right choice when so many couples seem to end up unhappy. It's impossible to know what the future holds and I think at the young age of nineteen it's very understandable for Anne to be influenced by Lady Russel, who has been her mother figure since Lady Elliot died.
It was very sad to read about Anne having to watch Wentworth court Louisa, I felt so sorry for her. Also at the end when Wentworth asked if he had come back two years later would she have accepted him and she said yes I was like ARGH! That's years of unnecessary unhappiness!
I really disliked the character of Elizabeth, I felt so sorry for Anne when she was stuck with Elizabeth and her father in the beginning. It was awful when Elizabeth said to Mrs Clay about how Anne was nothing to her and Mrs Clay was so much more important. I think she was my least favourite character in the whole book, maybe even including Mr Elliot! She was so cold and unsisterly!
A side note: I got really confused at the end of chapter 7. Anne was fretting over Captain Wentworth saying that she was "so altered that he should not have known her again." All of a sudden, it switched to Captain Wentworth's point of view. I was not expecting this at all, and I couldn't tell if it was actually him, or just Anne imagining what he must be thinking. That's the only thing that has given me trouble so far.
This actually really confused me too! I had to read over it a few times, at first I thought it was just Anne guessing what he was feeling and then I thought wait is this his point of view?
"Most people are other people. Their thoughts are someone else's opinions, their lives a mimicry, their passions a quotation." Oscar Wilde.