What’s the weirdest storyline ever to come out of Pretty Little Liars? There are so many — the dollhouse, the Jenna thing, Sydney, Emily’s stalker, Archer Dunhill — and for every one that I remember, I’m sure there are three that my brain doesn’t have room for. Of course, spoilers ahead for the series finale of PLL. It just can’t possibly remember them all. All of those storylines leave room for so many fan theories (which I love), and one of the most interesting was that Spencer’s twin was actually behind a lot of the tomfoolery of Rosewood. So, did Spencer have a twin on Pretty Little Liars? Heck yeah — and she's A.D.
This fan theory was speculated about a while ago, so I'm glad it was confirmed. Turns out, PLL has made so many references to twins over the past seven seasons. Jessica DiLaurentis has an actual twin, Mary Drake; Charlotte and Alison (and Bethany, too, actually) look like twins; and Spencer has exhibited some very un-Spencer-like behavior in recent seasons. Like at the airport, when she was talking to Wren? That didn’t seem like the harried Spencer that had just met up with Detective Furey. And when Hanna is kidnapped by A and Spencer talks to her, it didn’t feel like a dream. It felt like it was really happening, yet fans knew Spencer wasn’t actually there.
So, all of this was true: Spencer has a twin, and her name is Alex. Wren found her in a pub in England (she is English because she was adopted by an English family, but returned to the orphanage), and he was flabbergasted that she wasn't Spencer.
They got involved, he told her the story of Spencer and all the stuff they've been going through, and then it turns out that all of those moments that didn't seem like Spencer actually weren't. The kissing Toby, the giving Hanna a pep talk, etc. Yes, those were all Alex.
Alex is jealous of Spencer's friends and family, so she kidnapped Spencer and locked her in a room. Umm, she also killed Wren and made his ashes into a necklace, but not before using his sperm to impregnate Emily's eggs and put them in Alison. Spencer's twin sister Alex is A.D., and it's the best fan-theory-turned-real-life-plot I could have asked for.