In the latest episode of Pretty Little Liars, Spencer and Peter Hastings had a casual father-daughter chat during which he casually revealed that Mary Drake had murdered Jessica. It was a fairly anti-climatic moment because pretty much everyone suspected that Mary had offed her sister... but maybe it's more complicated than that. Ever since Mary made her first appearance on the show, there's been a fan theory that Jessica DiLaurentis is alive and pretending to be Mary on Pretty Little Liars. Peter's reveal about Jessica's death couldn't have possibly been more boring, especially because this has been one of the show's longest-standing mysteries — so there has to be more to the story. A brilliant theory formed by the hosts Bustle's Pretty Little Liars podcast Taking This One To The Grave suggests that Mary Drake's true identity could be the key to a number of major questions.
First of all, it's no secret that Jessica and Mary absolutely hate each other — so either would kill the other without batting an eyelash. Then there's the matter of Jessica absolutely despising the Hastings — what better way to torture them than by tearing apart the entire family? Sure, there's never a shortage of tension in the Hastings home, but Spencer's discovery that Mary Drake is her biological mom has been completely devastating for Peter, Veronica, and Spencer. (I'd ask how Melissa feels, but she's AWOL — doing something sketchy, I presume.)
Another major clue that Mary Drake is dead came from Charlotte herself. During her "big reveal," she was visibly emotional as she described finding her mother's body. She repeatedly stated "mom was the only one who loved me." We didn't know about Mary Drake at the time of the reveal — but Charlotte knew for a long time that Mary, not Jessica, was her mom. Although it remains unclear exactly how much contact they had, it stands to reason that she'd be way more emotional about Mary's death than Jessica's.
Much like Mary, Charlotte was wrongfully institutionalized and grew up at Radley. Meanwhile, Jessica's the one who put her there. Sure, she visited Charlotte and brought her clothes — but that's about it. If all this comes to fruition, another major plot twist could be in store — Jessica would have killed Charlotte because she was the only person who knew that she wasn't truly Mary Drake. The last thing in the world she would want is to have her cover blown, and Charlotte could have done just that if she'd survived.
I know I say this every week, but my mind is blown.