Best friends, secrets, and text messages. These are three powerful things and also the premise of Pretty Little Liars, the teen drama which aired for seven seasons from 2010 to 2017. After Alison DiLaurentis (Sascha Pieterse) is believed to be missing, her friends Hanna Martin (Ashley Benson), Emily Fields (Shay Mitchell), Aria Montgomery (Lucy Hale), and Spencer Hastings (Troian Bellisario) vow to dig deep and find the truth.

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While the girls date and go to school and have various personal dramas, they're also dealing with this mystery and receiving messages from a figure they call "A" who knows a lot about them. And they're shocked by twists and turns as well. Here are the five best and the five worst surprises on Pretty Little Liars.

Best: The Dollhouse Episodes

Spencer, Aria, Hanna, and Emily in fancy dresses on Pretty Little Liars

It was not only terrifying to watch Spencer, Hanna, Aria, and Emily wake up in identical bedrooms to their own and realize that they were trapped in a dollhouse, it was one of the best surprises on Pretty Little Liars.

The season five episode "Welcome To The Dollhouse" is really well-done, and as the characters realize that A created this environment, it's both disturbing and impressive. This was a storyline that fans couldn't have seen coming, and the stakes felt high, like maybe they wouldn't actually return home.

Worst: Spencer And Caleb's Romance

Caleb and Spencer crying on sides of a door on Pretty Little Liars

While many teen dramas feature various couplings over the seasons, like Joey and Dawson and then Joey and Pacey on Dawson's Creek, for example, the couples on Pretty Little Liars feel pretty set in stone. You have Aria and Ezra, Toby and Spencer, and Hanna and Caleb.

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Fans were in for a huge shock when Caleb and Spencer started a romantic relationship. They had bonded while hanging out in D.C. and while the storyline is handled with care, as they both feel guilty and Spencer even goes to Hanna to come clean about it, it's still kind of icky. Who dates their best friend's ex and the person that they have always been in love with?

Best: Melissa's Secret

A close-up of Melissa in Pretty Little Liars

Spencer's older sister, Melissa (Torrey DeVitto) , has always been a pretty mysterious character. The two have never got along that well and she was always away at school or working, so fans didn't really get to know her as well as the other girls.

Melissa has been carrying around a massive secret, though, and it's a huge surprise when she lets Spencer in on the truth in the season five episode, "No One Here Can Love or Understand Me." The liars find out that it wasn't Ali who was accidentally buried while she was actually still alive, it was a young girl named Bethany Young. Melissa spills that she did this. Why? To protect and save Spencer, who she believed had killed Ali. Yikes.

Worst: Ezra Writing A Book About Ali

Ezra wearing a baseball cap in his lair on Pretty Little Liars

Although it's easy to see Ezra Fitz (Ian Harding) and Aria's romance as creepy since, sure, he was many years older than her teenage self when they begun seeing each other, they have always had a really sweet relationship. He does care about her and they do seem to get along well, especially since they're both bookworms who love to write.

One of the worst surprises on the show is when Aria thinks that Ezra is on the A Team and then discovers the actual reason: he used to go out with Ali during his college days and then he wanted to write a book about the time when she went missing. What?! This was not a pleasant surprise for fans who would never want Ezra to love anyone other than Aria. And the fact that he was penning a book about Ali has a certain creep factor to it.

Best: Ali Comes Back

Alison sitting and looking sad on Pretty Little Liars

One of the best surprises on PLL is when Ali comes back. In the fourth season episode "Now You See Me, Now You Don't," the characters realize that Ali isn't actually dead. Emily asked the question that every fan had definitely been wondering: "If Ali's been alive this whole time, then whose funeral did we go to?"

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Ali is a focal point of the fifth season as she shares what she's been through with the other girls. It's scary to hear that she's been in hiding this entire time, and it would have been impossible to watch Ali come back to Rosewood without gasping out loud at the TV screen.

Worst: The Reveal Of Wren's True Nature

For a while, Wren Kingston (Julian Morris) seems like a sweet guy. But that's not really the case, which fans learn at the end of the show.

The fact that Wren has been in a relationship with Spencer's twin, Alex Drake, and part of the A Team is one of the worst surprises on the show. By this point, it felt like almost every character was actually evil or not who they said that they were, and the impact wasn't quite as powerful.

Best: Mona As A In The Season Two Finale

Mona smiling on Pretty Little Liars

In the second season finale, fans learned that Mona Vanderwaal (Janel Parrish) is A and she's the one who has been sending them text messages and making their lives totally miserable.

This might not have been a huge surprise for anyone who read the book series by Sara Shepard that the TV show is based on, as the same storyline is in the novels, but it was still a big "aha" moment. It made a lot of sense since Mona had been feeling insecure and she believed that Ali and the girls had to pay for their bullying behavior toward her.

Worst: Spencer's Twin, Alex Drake

Spencer and Alex Drake on Pretty Little Liars

The series finale of Pretty Little Liars had perhaps the biggest surprise of all: Spencer has a twin named Alex Drake, and she's also the figure that they refer to as "A.D." She kidnaps both Ezra and Spencer in the finale, which is especially inconvenient since Ezra and Aria are supposed to be getting married.

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It's safe to say that not everyone was on board with this particular storyline. It was a huge eyebrow-raising moment as it was meant to explain everything that had happened, but fans waited so long to get answers to who A was and who killed Charlotte. The "evil twin" thing didn't sit well with a lot of people. It felt like an easy explanation.

Best: Caleb Leaves Rosewood

Caleb looking serious in PLL

When Hanna's one true love Caleb Rivers (Tyler Blackburn) leaves Rosewood, it's actually so the character can star in the spin-off Ravenswood.

While it was super sad to see Caleb break Hanna's heart by leaving, it was also a really interesting plot point since, as people say, distance makes the heart grow fonder. Everyone loves a dramatic teen romance on a show like this and these two characters delivered.

Worst: Toby And Yvonne's Engagement

Toby Cavanaugh (Keegan Allen) and Spencer are a couple who have been shipped by countless PLL fans. It's pretty surprising when Spencer learns that he's engaged to a girl named Yvonne Philipps (Kara Royster) in the sixth season episode "New Guys, New Lies."

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This is a big shock as no one would have expected him to move on from Spencer and want to marry someone else. Sure, Yvonne passes away in a tragic storyline, but that's after she and Toby become husband and wife. It seems strange that this character would make this choice.

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