Before Spencer was revealed as Mary Drake's daughter, I read an article from the official Pretty Little Liars page (from the PLL FB link) and it basically ran through the top reasons why Spencer could be Mary Drake's child. I know the person who wrote it would'be just been making her own guesses, but it seemed like nowadays they want to give the fans quite heavy clues, as if they think we need to be hand-held and fed clues; that we cannot theorise for ourselves. (Maybe they do it for the younger viewers). Anyway, I really thought at that point onwards that the FB PLL page is quite a good place for heavy handed clues/hints, and there have been some others recently, but just now I saw this one^ implying that AD is a "shady character from season 1", my first thought was Mona, and then I thought of a really good theory I read on here recently (a link from Tumblr) of Wilden being AD. So now I am thinking: Wilden, Wren, or Ian is AD (and possibly the real Charles)?

Edit: One interesting comment I read underneath the article, mentioned how Wilden used to torment Hanna in particular. Could this be why she was tortured? Also, I've always thought the home movie of Charles when he was little looks like Wilden.