Pretty Little Liars has always been about the mysteries: Who is A? Who is A.D.? Who will end up together? The June 27 series finale delivered answers aplenty, but the show's lasting legacy has nothing to do with its many twists — it's about the people who have spent seven seasons trying to decipher them.

Pretty Little Liars was arguably the first series to capitalize on the rise of social media as a medium for discussion, debate and obsessive analysis of a show as it aired — seven years after it debuted, it's still the "most social TV show" in TV history, racking up more than 256 million engagements across social platforms last year, beating The Walking Dead's 145 million.

Because of that fan fervor, live tweeting became a cottage industry that now dominates every major televised event (ABC even made a whole marketing strategy out of it with Shonda Rhimes' #TGIT programming block), and showrunners receive social media training specifically to teach them how to engage with fans online. Stars use Twitter Q&As and Facebook Live segments to tease upcoming episodes, and writers and directors post snippets of script pages or behind-the-scenes photos on Instagram and Snapchat to hype viewers up before the show airs.

In short, Pretty Little Liars forever changed the way TV fans, creators and networks use social media, and showrunners are still grappling with all the ways that Twitter, Facebook and other emerging platforms have affected what they do and how they do it.

Image: socialguide/abc family

PLL has always been a solid ratings hit for Freeform (formerly ABC Family), but the cast and creators' willingness to engage with their fans encouraged a passion and loyalty that few shows can rival, constantly keeping the show in the zeitgeist even after seven seasons of twists and fakeouts.

For PLL showrunner Marlene King, using Twitter has always been about connecting with the audience. "It's a great way for me to get to know fans. We get a lot out of hearing their feedback," she tells Mashable. "We create the shows for them, so hearing how much the show has meant to them or how it has helped them with their struggles, for me that's the best thing about social media."

How showrunners engage with the many-headed beast that is social media can now make or break a series — in May, fans of NBC's Timeless literally persuaded the network to un-cancel the show, three days after the Peacock pulled the plug on the time-travel drama.

"[We] woke up the next morning, all of us, and heard from fans and the outcry and we thought, 'Well, let's figure out how to try to bring it back,'" said NBC Entertainment Chairman Robert Greenblatt in a conference call with reporters after the renewal news broke.

Its true. NBC canceled #Timeless. We're surprised & upset. Get you a longer response later. Odds are long, but trying to find another home. — Eric Kripke (@therealKripke) May 10, 2017

The #TimeTeam went back 3 days, and changed history. @nbc picked us up for 10 episodes. Seriously. Airs next summer. #TimelessRenewed pic.twitter.com/SDkeShlByL — Eric Kripke (@therealKripke) May 13, 2017

This isn't a joke! They legit heard from the fans and changed their minds! https://t.co/VMfnmTSIDH — Shawn Ryan (@ShawnRyanTV) May 13, 2017

But that open channel between creatives and fans is a double-edged sword that can sometimes lead to entitlement, bullying and harassment from a small but vocal minority who feel ownership over a show's storyline or characters. Last year, Pretty Little Liars star Sasha Pieterse opened up about the body-shaming she experienced from fans after she gained weight due to a hormone imbalance.

Still, social media can also be a force for good — allowing stars and fans to collaborate on charitable endeavors, resurrect series from cancellation, and bring people together to form a like-minded community and forge lifelong friendships. Like any technological advancement, there are pros and cons.

And no one is more aware of those positives and negatives than the people behind the scenes — the showrunners whose series have some of the most vocal, passionate, and, yes, occasionally critical fanbases on the web.

In addition to King, Mashable talked with Bryan Fuller, showrunner of NBC's canceled (but still beloved) Hannibal and Starz's new hit drama American Gods; Marc Guggenheim, executive producer of The CW's Arrow and Legends of Tomorrow; and Ron Moore, who helmed Syfy's fan-favorite Battlestar Galactica reboot and currently runs Starz's Outlander, to get their take on how social media has made their jobs simultaneously easier and so much harder over the past few years.

Pro: Instant Feedback

All four executive producers agreed that the ability to take the temperature of their audience is one of the most positive aspects of social media they've encountered since Twitter and Facebook gained popularity.

"I've always tried to embrace it, because it is instant feedback, which we're really lucky to get, and we've been fortunate enough that usually it's positive," King says of PLL. "But occasionally we'll make choices that a certain group of fans aren't happy about and the negative comes with that. They're allowed to disagree with our choices so long as they're not rude or belligerent about it. It just comes with the territory, the good and the bad."

Moore, an industry veteran who cut his teeth on the Star Trek franchise, working on The Next Generation through Voyager, recalls the days when producers would have to turn to a focus group if they wanted feedback from viewers. "It’s great to be able to have that immediacy, to get quick feedback from the audience, to have their thoughts and ideas and reactions at your fingertips when you want them," he says.

Fuller, whose last two series have both been adaptations of preexisting works, can identify with his audience's fervor, because he considers himself a fan too. "I appreciate the personal connection with the audience. I'm generally telling stories in genres that I'm also a fan of. For me, it's not so much that there is a hierarchy of 'show creator' and 'show watcher' as much as it is fellow fans of material, particularly as we get into a highly sentimentalized area of storytelling where we're constantly seeing remakes and revisitations to previous properties," he explains.

"A lot of people who are engaging in the conversation have a previous experience with whatever subject matter it is and have an opinion. I think if you can get into a dialogue where it is the sharing of opinion as opposed to the drowning out of conflicting opinions, then it's an exciting place to discuss and discover things about what you love that you hadn't realized before."

Con: Instant Feedback

But, as Guggenheim points out, instant feedback can be as negative as it is positive. As an executive producer on both Arrow and Legends of Tomorrow — two superhero shows with avid fanbases — he has firsthand experience with the contrasting ways that viewers can react to a show, depending on whether or not a storyline is fitting their preferred narrative.

"Legends is so much less controversial online than Arrow is. The experience in terms of dealing with the fans on those two shows is night and day," he admits. "With respect to Legends, I never think about social media. There's a lot of social media engagement with the show, but the content of it doesn't really require me to think about, 'Well, what are the fans going to think?' Arrow is a much more complex circumstance."

While Arrow stirs up a lot of emotions among its fans, Guggenheim and Fuller both agree that there's a troubling amount of cruelty and vitriol inherent in online interaction — at least when users are able to comment anonymously.

"My Twitter feeds into my Instagram, and my daughter will read my Instagram feed, and she'll read the comments," Guggenheim says. "[Recently] she came up to me and she's like, 'Daddy, why do people want you fired?' I'm like, 'They don't want daddy fired. They just want daddy to have a vacation.' It's like, you want me fired. You want me dead. You want me to kill myself. I read all of that. It's a TV show. Let's put it all in some kind of perspective."

Fuller agrees, "I'm always surprised by the insightfulness and the intelligence of the audience members that I've engaged with on Twitter personally. That is more my experience than the occasional, 'Why did you do that? You're a cunt,' which I've been called by different people."

He adds, "The interesting evolution of these fan communities is that the anonymity does give you the perception of freedom to attack from a sniper's post, unseen in the distance. The dilution of that toxicity comes from the personal connections that are maintained and grown through these interactions online, where I see Fannibals that I have chatted with interacting with other Fannibals and being incredibly supportive."

Basically, like all communities on and offline, fandoms need to police themselves and hold each other accountable for abusive behavior, because the platforms themselves can't always be counted on to do it for them.

Pro: Promotion

Thanks to social media, we now have a better sense of what's going on behind the scenes of our favorite shows than ever before, mostly due to posts from the cast and crew. For shows like Game of Thrones and The Walking Dead, every new image, trailer, behind-the-scenes video and official Tweet could contain clues for the upcoming season, and fans scrutinize them carefully.

Moore says that platforms like Twitter and Facebook have become "a big component of how you put information out there; when the show’s on; where it’s on; what’s coming up; how to tease things; when you make casting announcements — social media is deeply embedded in that now."

That's obvious in the way the official Outlander social accounts engage with fans — the show has already dropped Season 3 hints and sneak peeks via social videos, and even if fans aren't attending San Diego Comic-Con this year to see the show's panel, they can still participate in the fun by voting on an upcoming t-shirt design.

Be a part of #SDCC2017, even if you can't attend. Vote on which #Outlander shirt you'd wear for a chance to get one of your very own. — Outlander (@Outlander_STARZ) June 23, 2017

This interaction between official accounts and fans is vital when shows aren't airing, to keep the audience engaged and excited before the series returns — and it's equally important when a series returns to air, to encourage fans to watch live and help cut through the clutter of rival shows that may be jostling for their attention. Social media has now become a way to "eventize" every episode, especially for twist-laden shows like PLL and Scandal, when viewers want to feel like they're part of the conversation as it happens.

Some studios and networks might consider their social-savvy talent to be a little anxiety-inducing, given that information can be so freely and widely disseminated, and Fuller admits that he's sympathetic to their plight.

"The delivery mechanism of press releases is harder to control for a studio and a network because you have showrunners who don't need to go through the publicist or the marketing department at the studio or the network in order to make the engagement," he says. "I think that has changed quite a bit, and you'll see some studios and networks offering social media training and what to say and what not to say — which are fundamentally common sense issues, but you're dealing with an industry filled with artists and egos, so there are occasional slips of social graces."

Still, it's clear that some showrunners relish the freedom of being able to promote their series directly to their audience. Ryan Murphy — creator of American Horror Story, American Crime Story and Feud — has made a habit of breaking casting news and teasing fans via his Instagram posts, leading fans on a scavenger hunt for clues throughout his social feed.

American Horror Story Season 7 tease. A post shared by Ryan Murphy (@mrrpmurphy) on May 5, 2017 at 7:28am PDT

Con: Spoilers

Any TV fan who lives on the West Coast has likely been inadvertently spoiled by forgetting to stay off Facebook or Twitter while their favorite show is airing on the East Coast, and the rise of live tweeting has only made it harder to avoid those surprise plot twists.

"I think the spoiler factor is huge," Guggenheim says. "In fact, I see a lot of people tweeting out, 'Okay, I'm going offline, because I don't want things spoiled tonight.'"

It's hard for showrunners and networks to combat spoiler culture, in part because a lot of the appeal of Twitter is the ability to react to something in real-time, with a community that's just as invested as you are.

Fuller's form of compromise, in terms of making sure that no viewers feel left out, is to live-tweet both the East and West coast airings of his shows.

"The East Coast would have a much higher engagement than West Coast, partly because some people have satellite feeds and are watching the East Coast feed. Others are just watching and not worrying about what's happening on social media," he recalls of Hannibal. "It really is about, what is the experience that you want to have when you're watching a show? Do you want to have a community experience? Do you want to have the narrative experience? You can have either. It's entirely up to you."

On a practical level, any fans who are actively seeking out spoilers are likely to find them, if they're motivated, but King says the Pretty Little Liars team did try to take precautions against leaks as the show gained popularity, at least before the episodes aired. "We definitely got more savvy over the years in terms of protecting spoilers. There were a couple times when things were somehow leaked and fans found out about them," she says. "But then we realized most fans don't want to be spoiled, so that worked out OK. But we did have an ex-CIA guy come in and do all of our computers so we couldn't get hacked or anything."

Pro: Community

Beyond giving them a channel for immediate feedback, all four showrunners emphasized the value of social media as a way of creating bonds between audience members, allowing fans to find a community of like-minded souls.

"Growing up as a fan of certain genre material, all I had was Fangoria magazine or Starlog magazine to tell me that there were others out there who thought similarly, as fanatically, as I did. Yet I had no real way of contacting them beyond like, 'Want a penpal?' on the back of the magazine, and usually those don't bear much fruit," Fuller recalls. "It's so much more accessible and so much easier to engage on Twitter to find friends."

"We are, as storytellers, in the business of curing loneliness and disconnection. Social media helps people connect."

Guggenheim agrees, "I've had a lot of really positive fan interactions on Twitter ... I grew up reading comic books where your fan interactions were going to a convention or writing a letter. This is wonderful. This is instantaneous, and it's bilateral. I can talk to fans, and fans can talk to me."

Identifying as a member of a fandom on a social platform is both a badge of honor and an invitation for fellow travellers, which is why so many fans proudly display their affiliation and shipping preferences in their bios.

There are Fannibals and Trekkers and Browncoats aplenty, while Supernatural fandom refers to itself as the #SPNFamily; a moniker that has been adopted by the cast and creative team as a way of emphasizing that the fans are integral to the show's success and longevity, and that "family don't end with blood," as our beloved Bobby Singer would say.

A perfect example of SPNFamily solidarity: After Supernatural star Jared Padalecki opened up about his personal experience with depression and launched the Always Keep Fighting fundraising campaign, fans showed their support at Comic-Con by raising thousands of electric candles up into the air in a touching sign of solidarity.

"I love checking a Twitter feed and seeing groups of Fannibals who are watching another show together, and they're all commenting on it and like, 'Oh my God, I just died,' where I'm just like, 'How great that they get to have this virtual pajama party where they're all cozied up in front of the screen and sharing entertainment,'" Fuller says. "We are, as storytellers, in the business of curing loneliness and disconnection. Social media helps people connect. There's always a community out there for you to engage in that is positive and supportive if you can find it. You see so much online bullying and the ugly, toxic places that people will go to in social media through the protection of anonymity, and you just want those who are feeling oppressed by that to dig a little deeper to find the friendlier faces and learn how to block."

Moore has come through many fandoms over the course of his career, and notes that while social media has had an impact on how fans engage with the shows they love, "the tools have changed, but fandom has not."

"It comes from a place of love, which is a place you have to remember when you’re on this side of the curtain, because whatever you’re hearing from fans, good or bad, you have to remember it’s all coming from a place of, they love your show, they love the characters, they love the stories, and when they’re upset, it’s because they’re upset that something happened to something that matters to them," he says.

"They still organize themselves into groups, they still gather together physically at conventions. Social media hasn’t destroyed that need for fans to get together to make their own costumes and props; to make their own recreations of things they see on shows; and to argue incessantly about the canon of the show; the trivia of the show; to find the flaws in the show; to want to know exactly how some particular favorite scene was made; what were the funny stories associated with it. All of that is like fandom eternally. They just have a new way of expressing it and an immediacy to reaching out across those distances in real time that they didn’t used to."

Con: Ownership

As much as showrunners recognize and appreciate that their projects wouldn't be on the air without their fans, there is a dark side to that dedication, when love morphs into possessiveness, prompting fans to attack a show's cast or writers over narrative choices that they don't agree with.

All four producers emphasized that they don't let fan reaction — especially negative feedback — affect their storytelling, no matter how eager some fans are to claim credit when a show seems to pivot in a direction they prefer.

This is an issue that Guggenheim has struggled with as Arrow has progressed, and he's candid in explaining why it's a losing battle to try and satisfy one subset of the overall audience, no matter how loud they might seem online.

"I'm always saying, and I think the show proves, we really don't write with social media in mind, for a few different reasons. First of all, as a matter of principle I don't agree with that. I write for the kind of audience that I am. The way I watch television, and movies, and read comics, is: I consume entertainment to be entertained. I may have an opinion, I may want to see a certain result, but at the end of the day I've never been the kind of fan that needs to see something happen a certain way, or see a certain couple get together; I'm not outraged about a certain plot twist," he says.

"I understand and respect the fact that there's a lot of members of the audience out there that feel like, 'Well, we watch your show. Therefore, you're the reason we're a hit. Therefore, we should have a vote.' I can track the logic of that, but I'm not their showrunner. That's just not me. Also, the other thing that I have to keep in mind is Twitter is a certain self-selecting audience," he points out. "Just with respect to Arrow, the views reflected on Twitter are different from the views reflected on Facebook, which are different from the views reflected on Reddit, just to take three very specific platforms that I know have very specific points of view. Even if I were inclined to listen to social media, the next question would be, well, which social media do I listen to? I can tell you, and I think logic would tell you, there is no making all three of the people on those platforms happy. It's kind of a sucker's bet to change your show based upon social media."

Moore agrees: "I try to keep a pretty solid firewall between all of that and our writers’ room, because I think it’s really easy to be influenced by what, in reality, is a handful of voices – you can only take in so much."

He notes that he's become somewhat "inured" to the feedback because he began his career with Star Trek, where he observed the potent effect that outside opinions could have on a writers' room.

"Even in those days when I was on Trek in the '90s and the internet was still in its infancy and we were getting used to blogs and people posting on different forums, the writers would read those reviews somewhat obsessively, and of course, being writers, we all obsess about the bad reviews," he laughs. "You just saw the dynamic form in the room – ‘well the fans don’t like this, the fans do like that,’ and quickly we all started to go 'what are we doing? This is insane.' For that experience I just take a hard line on it, and if anyone brings it up in the writers’ room I shut ‘em down pretty quickly."

That might be frustrating for viewers, especially when their desires don't align with a writer's, but as Moore points out, "It’s not a democracy, that’s not how this works. We’re creating this show, we give it to the audience, and then the audience makes their determination after the fact, but I don’t want them at the front of the process."

"The other thing that I think social media completely misses," Guggenheim adds, "is we write so far ahead of broadcast, to the point where the things that people are complaining about, that die is cast, for better or for worse. It's very nice to get feedback, but the truth of the matter is that there's really no way to turn the oil tanker. The show is what the show is by the time people are watching it."

Ultimately, there's a covenant between TV shows and viewers: Showrunners are entitled to produce and write a series however they see fit, and viewers are entitled to stop watching if the show stops being enjoyable for them.

"Don't like it, don't watch" may be a simplistic response, especially when fans have invested years into a particular character, relationship or storyline, but it also seems like the only way for producers and audience members to maintain their sanity in a TV landscape that offers increasingly varied choices for entertainment.

Petitions and social campaigns may have an impact when it comes to saving a bubble show, if enough fans can demonstrate that there's a bankable interest in the series moving forward, but like it or not, the TV business is indeed a business. Short of advertisers pulling out of the show or viewership declining dramatically and consistently over the course of a season, it's hard to prove that a disagreeable storytelling choice is having an adverse effect on a show's quality or durability.

That certainly doesn't means that fans should stop expressing themselves on social media — but there are ways to do it respectfully, without telling a writer or producer that they should kill themselves.

"I think access is wonderful. The vast majority of writers and showrunners that I know, they love it. They love interacting with fans," Guggenheim says. "Where it starts to come off the rails is when the people who have access to you are abusing that access and just acting rude. I think the one thing I would love to see us do as a society is strip away the distinction between in real life, 'IRL,' and online when it comes to social mores. If you've been raised properly, you know something about manners. You know the right way to treat people. Don't say something online that you wouldn't say to someone else's face."

Pretty Little Liars has certainly toyed with viewers' expectations over the years, often resulting in backlash, but in King's eyes, every twist served the overarching plot, whether fans liked it or not.

"I didn't second guess it, but fans were devastated when we revealed that Toby was temporarily working on the A team. I knew eventually that was going to go full circle — we would find out that he was working for the greater good — but it was difficult to see how upset the fans were for so long until we revealed that he was actually working for the greater good. But we stuck to our guns and stuck with the storyline," she recalls.

Still, for storytelling choices that don't affect the endgame, a benevolent writer might throw fans a bone if they notice that something is still resonating with their audience after a season has concluded — like a relationship that originally wasn't designed to be long-term. But King might be the exception, not the rule.

"I think maybe relationships have been affected in the sense that you can tell when fans really embrace a couple together," she adds. "And why not keep them together and make everybody happy? Most people. Not everybody."

Pro: Hope

Today, perhaps more than ever, social media is a minefield, where expressing your opinion could cost you your job, and bad behavior rarely goes unnoticed — but the prevailing sentiment among the showrunners is that the positives of the medium far outweigh the negatives. After all, as Moore and Fuller point out, whether you watch TV or create it, your passion stems from a place of love — we're all fans, otherwise we wouldn't devote so much time and energy to these stories.

Social media may breed contempt when antagonistic voices are caught in an echo chamber, but it also encourages creativity, friendship, discussion and, hopefully, a sense of opportunity for fans who aspire to launch their own dream project someday.

"For those of us growing up before social media, there was a magic to the entertainment industry, that only fairies and wizards were able to cross those gates. It seemed unattainable. It didn't seem like a realistic job to achieve," Fuller says. "What being on social media does is, you're able to see the audience in the way that you can in the theatrical experience, standing on the stage and looking out and seeing a face that is responding to what they're seeing.

"For the casual Twitterer who tweets to a showrunner who, in some of their perceptions, does a magical, complicated thing that they don't entirely understand... when that person turns around and sees you and engages with you or offers you a virtual hug or a vote of confidence, in some way you feel like, 'Oh, there are people on the other side of that wall who know I exist, which means I can climb that wall.'"

So regardless of whether you agree with the direction of your favorite TV show or not, don't stop climbing.

With reporting by Andrea Reiher.

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