Mary Drake (Andrea Parker) has officially solidified herself as one of Pretty Little Liars' most mysterious characters — and that was before she announced that she was Spencer's (Troian Bellisario) mom. Mary's sketchy past (was she really framed for the death of her babysitting charged by her evil twin?) and questionable intentions (just how closely was she working with Archer?) have made her both a suspect for Uber A and another potential victim of the royally effed-up DiLaurentis family. So what's the truth? We won't know for sure until Pretty Little Liars returns in April for its final 10 episodes, but a new fan theory suggests that we'll get flashbacks to Mary's time in Radley Sanitarium.