She's just found out that Mary Drake (Andrea Parker) is her biological mother, which changes how she feels about her entire life. Everything she's ever known has turned out to be a lie, but according to Bellisario, the revelation also makes a ton of sense.
"She's always felt like the black sheep of her family," the actress told TVGuide.com at the Freeform Upfronts red carpet on Wednesday. "Now she has this piece of paper, which might be A.D. playing a trick on her, but also seems to fill in a lot of the blanks of how she has felt her whole life."
That piece of paper is the letter that Mary Drake allegedly wrote when Spencer was born and A.D. delivered to Spencer as a reward for starting A.D.'s board game. The problem is that with A.D., you never know what's the real truth and what's been altered to manipulate the girls into the next phase of the devious stalker's plan. Spencer knows just how tricky A.D. can be, so she's taking any "gifts" from the hooded figure with a grain of salt.
However, anyone would be curious to know more about where those "gifts" came from once they've delivered a revelation like Spencer's. The most rational Liar is going to have to weigh her pragmatism against her natural instinct in the final episodes as she battles to one-up A.D. and find out who she really is at the same time.
"That is something that a lot of people experience when they find out who their biological mother might be. You want to know more about them. You want to know what things are similar and what things are different," Bellisario explained. "That's going to be a very strong pull even though Spencer doesn't know if this person is ultimately dangerous or not."
Pretty Little Liars continues Tuesdays at 8/7c on Freeform.
Additional reporting by Sadie Gennis.