Showrunner I. Marlene King sat down with TVGuide to discuss Season 6B of the ABC Family mystery series, and while she stayed tight-lipped about what to expect from the second half of the season, she did drop a major truth bomb. Here's what she told TVGuide:
Let's analyze this quote for a moment, shall we? It's very interesting that King used the word "related" as opposed to "connected" or "working for." Perhaps that's a clue in itself: could the new villain be a family member of one of the characters we already know?
By the end of [Season] 6B, you will pretty much know who or who's related to this big bad.
It's certainly possible, given Pretty Little Liars' history of introducing us to secret, and often completely random family members. (Wes Fitzgerald, what's good?) While I hope that the DiLaurentis' don't have another secret kid that they're hiding in a mental hospital somewhere, I wouldn't be surprised if we were introduced to a relative of one of the girls' with a nefarious agenda. That's so classic PLL, and if Aria's uncle comes to Rosewood in a black hoodie, well, just remember that I told you first.