For someone who's only been back in Rosewood for a few hours, Jenna Marshall's return to Pretty Little Liars has already been chock-full of exciting twists and turns. Take, for example, the fact that she just so happens to know Rollins' real name is Archer Dunhill, proving yet again that even though she's been off our screens since Season 5's Masquerade Ice Ball doesn't mean she hasn't still been heavily involved in the A game this entire time. But while it'd be easy to assume that Archer Dunhill is the mysterious A.D. texted the Liars have been dealing with all season, I'm not so sure that's necessarily the case. This series never lays all of its cards out on the table at once, which means it's highly possible that Jenna is Uber A on Pretty Little Liars and has been all along.
Let's face it — Jenna has a longstanding history with the Liars that goes all the way back to their early days in high school. (You know, like the time their prank with a stink bomb caused her to go blind?) So her motives for wanting to torment the Liars certainly wouldn't be in short supply. Not to mention that it could also help to explain how this new stalker seems to know so much about them and their personal lives since she's been a witness to their many misdeeds since pretty much Day 1.
The only flaw I can see with this theory is that it doesn't help to explain how Jenna came to meet Rollins. (I mean, Archer.) Normally, I would say their connection would come from the fact that they both know Charlotte, but Jenna and Charlotte didn't get along in any capacity. Jenna was even afraid of Charlotte at one point, so why would she be so invested in what happened to her? If anything, she should be considered a suspect in her death. And yet, Uber A has been desperate to find Charlotte's killer and avenge her death.
The only explanation I can think of is that perhaps Jenna was secretly in love with Rollins and has been using her Uber A identity to help him track down Charlotte's killer, not because she cares about the answer, but rather to curry favor with Rollins himself. Maybe she hoped finding answers would help bring him closure so that he could move on and be with someone else... like her.
We know that Jenna can get very possessive over the people she loves (looking at you, Toby), so it wouldn't be out of character if her feelings for Rollins helped to motivate her Uber A scheme. Plus, Rollins always seemed to know whatever A.D. discovered really quickly. When the Liars told A.D. that Alison had killed Charlotte, Rollins immediately accused her of the crime. Sure, this could've been because he himself was A.D. But perhaps it was because he was in direct contact with Uber A, who would relay all of they intel immediately to him. And considering he was close enough to Jenna for her to know his real identity, I'd say that makes her a more than likely candidate.
Tammin Sursok , who plays Jenna on the series, recently spoke with Cosmopolitan.com about her grand to the show and teased that Jenna is "definitely involved in a lot of exciting, tantalizing things that the viewers want answers for." Having her be Uber A would certainly fall under that category. But, as always, Jenna remains just as mysterious as ever. So until we figure out what exactly prompted her return to Rosewood, I'm afraid all we have is guesswork and speculation. Welcome to the wonderful (and aggravating) world of PLL!