She's always been enigmatic, whether it was when she was flirting with Emily after swim practice, or twinning with Jenna at the Brew. But who is Sydney Driscoll from Pretty Little Liars, again? With Rosewood's revolving door of mysterious guest characters, it can be tough to keep track of who's who — what storylines they were part of, which characters they were allied with, etc. As fate would have it, Sydney will actually be returning to Rosewood for Season 7B — so it's important to get back in touch with the character before she starts acting all mysterious and suspicious again.
So, starting from the top? Sydney was first introduced back in Season 5. She arrived on the show to much heralding — showrunner I. Marlene King even told International Business Times:
We first met her as a swim teammate of Emily and Paige's — for a spell, it even seemed like she might be interested in Emily — but then, the Liars caught her impersonating Jenna, and things quickly grew chilly. She was also revealed to be a member of Mona's Army — a group of characters (including other familiar faces, like Lucas and Jenna) that distrusted Alison and her return to Rosewood. Basically, her main role in the show seemed to be dressing up like Jenna, acting shady, and trying to pit the Liars against each other.
She also appeared in "When the A Stole Christmas — remember, this was right after Mona was "killed," so you can imagine that her namesake army wasn't exactly happy with Alison and the rest of the Liars. Most recently, she made an appearance in Season 7A's "The DArkest Knight" — where she came back to Rosewood to briefly impersonate Jenna, in order to confuse Caleb and Mona, who were following her at the time.
All in all, she's always been something of a baffling presence on the show — so her return could basically mean anything at this point. One thing's for sure: whatever she's in town for, it doesn't exactly bode well for the Liars — the probability's high that she'll be stirring up the drama again. And who knows? Maybe she and Jenna will pull off another switcheroo — heck, maybe she'll even shed light on the whole "Is Jenna A.D.?" situation in the process.