7 Things We'd Really Like to Know Before the End of Pretty Little Liars

By now we know there is, in fact, someone sinister at the very bottom of this whole mystery: a figure who identifies as "A.D." But to what extent is this person involved?

Does A.D. trace back to the beginning? Is there a reason we haven't heard of them until now? What does this mean for the now defunct "A" team? Do the initials line up with the myriad characters with a D last name, like, uh, DiLaurentis? And furthermore, how does "A.D." tie in with the Carissimi Group, Mary Drake, and Dr. Rollins?