Spencer Hastings Could Absolutely Be "A.D." on Pretty Little Liars, and Here's Why

The Hastings family has buried quite a few secrets over the years. The completely covered up the fact that Peter Hastings had an affair with Jessica DiLaurentis, and that Jason DiLaurentis is actually Spencer's half-brother. Mary Drake hints to Spencer that they met when she was very young — clearly, the Hastings family's connection to Mary Drake goes way back. If Spencer is, in any way, entangled in Mary Drake's web, her intentions may be much more sinister than we realize.