Wetpaint Entertainment caught up with Troian Bellisario of Pretty Little Liars, and Troian teased that we'll get to learn an interesting secret about Spencer - that will ultimately conflict with her relationship with Toby.
“You get to learn the most fun secret about Spencer, and that’s why wasn’t she with the rest of the girls when they woke up and why was she awake to hear Alison scream. As we’re going through the season you’re hearing a lot more and understanding more about the night and Spencer’s state and why she had the fight with Alison.”
“[Spencer and Toby] definitely go through something really, really difficult which is this big secret that is revealed about Spencer and that comes between them. Spencer has to make a choice to be open and honest with him or to keep it a secret and maybe go even further down this dark path. It definitely drives a wedge between them.”
Troian also spoils that Spencer has a "very Patrick Bateman moment" coming up in a later season 4 episode that gets "messy". Another scene like when Spencer went all crazy on Janel Parrish's Mona, perhaps?
What do you think Spencer's secret could be?