Mad Men S6 Don

Editor's Note: This post is presented in partnership with WGN America and its new series "MANHATTAN," premiering this Sunday at 9pm ET / 8pm CT. 

A character with a secret can make for the most fascinating of television – and those secrets, whether slowly revealed or suddenly exploded, can take the average drama and accelerate it into the annals of television. What are some of modern TV's most captivating moments, fueled by what characters kept to themselves? Check these out.

"The West Wing": President Bartlet has M.S.

Any secret President Bartlet kept from his best friend/Chief of Staff Leo McGarry had to be a doozy. While he found out about the President's diagnosis of Multiple Sclerosis halfway through the first season, Leo was in the dark for nearly seven years in "The West Wing"'s timeline.

Writer/creator Aaron Sorkin ultimately revealed the secret in carefully calculated doses over the course of the first two seasons, providing varying reactions from the staffers in order to prepare the audience for how a fictional population might respond to such a revelation.

Some handled it well -- Leo and Josh in particular sided with viewers' immediate reaction of sympathy and concern -- while Toby, always a hell-raiser on the show, treated the news with anger both understandable and unexpected. The methodical unveiling added to the drama of the secret, building to a Season 2 climax for the ages with President Bartlet facing off against an angry press corps -- and a storm-raging God -- as he's about to decide whether or not to run for a second term. It's "The West Wing" at its best, and an ideal lesson in how the unveiling of a secret can lead to character development. 

"The X-Files": Who's the father of Scully's baby?

'The X Files': 'all things'
'The X Files': 'all things'

When the Season 7 finale "Requiem" aired, savvy "X-Files" viewers were aware that the episode would contain a big change for the series, as it had been announced that star David Duchovny would be shifting to a limited presence in the next season. Thus, Agent Mulder's alien abduction was not much of a surprise -- but then, in the final moments of the episode, Agent Scully revealed that she was pregnant.

While there were hints that Mulder and Scully had become closer than friends over the course of the season, there was no official indication that they'd started a sexual relationship, and also Scully had previously believed herself to be infertile. The show would continue to keep Scully's son's origins to itself for at least another season -- and even after that, how exactly William came to be remained unclear. 

"The Wire": Howard "Bunny" Colvin's drug free zone

One of the most controversial plot lines of David Simon's flawless cops and robbers' saga "The Wire" was when Major Howard "Bunny" Colvin stretched the rules to the point of breaking by enacting a "drug-free zone" known as Hamsterdam in one of the worst crime districts of Western Baltimore. For his character, the move actually made sense: Simon framed Colvin as under pressure to post a reduction in crime rate, legally or otherwise. He may have refused to "juke" the stats, but he didn't balk at breaking the rules for the betterment of his city. Bunny wanted to leave the city better off than when he started on the force. With retirement on the horizon, Hamsterdam was the only solution he could see.

Realistically, the plot is quite plausible. Experimentation of a similar fashion has been attempted in various areas around the globe, and Baltimore Mayor Kurt Schmoke even called for drug legislation during his tenure from 1988 to 1999. Simon could have easily pulled the idea from any number of sources, enacting it for the betterment of a society more eager to listen to political solutions acted out in a fictional -- if quite realistic -- television reality. Still, the exposure of Bunny's attempted solution brought a tragic end to the well-liked character's long tenure on "The Wire."

"Mad Men": Don Draper is Dick Whitman

It's not until the penultimate episode of Season 1 that we discover for certain that Don Draper, the marketing genius with a penchant for women and whiskey, isn't Don Draper at all. He's Dick Whitman, an unassuming orphan who saw an opportunity for a better life after the war and grabbed it with both hands. Through a box of his brother's belongings, Pete Campbell figures out who Don/Dick really is and threatens to expose him if he doesn't get the promotion he thinks he's entitled to after two-and-a-half years at the firm. Then, via flashback, we learn of Dick's theft of the real Don's dog tags, right from the charred body of a Lieutenant in the U.S. Army.

All at once, it's as if the main hook of "Mad Men" has disappeared. Our questions have been answered, at least to the point of immediate satisfaction; where the show would go from there became the question, even as other characters had developed and plot lines were introduced. Creator Matthew Weiner risked a lot by informing his audience of his lead character's dark past before the first season even wrapped -- but then again, he knew there was much more in store regarding Don, er, Dick's existential crisis. Sometimes the first secret is just the tip of the iceberg. 

"Manhattan": Just what, exactly, is the Manhattan Project?

WGN America "Manhattan"

When the families of scientists enlisted for the Manhattan Project arrived in Los Alamos, New Mexico, they had no idea why they'd been brought to the middle of the desert for a mysterious government project created under the authority of the Department of Energy. All they knew is that they weren't allowed to leave their tiny military outpost, and that any questions they asked would go unanswered.

That's because these husbands and fathers could not reveal the true nature of their work: Engineering the components that would lead to the world's first atomic bomb. The "gadget," as it was referred to, was developed under the highest levels of secrecy -- because the stakes were also of the highest level. The Manhattan Project would eventually lead to the creation of the bombs that would end World War II (at the cost of Hiroshima and Nagasaki, Japan). 

"Game of Thrones": Who is Jon Snow's Mother?

In the first season of "Game of Thrones," as they each head in different directions, Ned Stark tells his bastard son Jon Snow that the next time they met each other, Ned would reveal the truth about Jon's mother.

This, however, proved to be the last time the two characters would see each other, due to Ned Stark's pesky sense of nobility. Four seasons later, viewers still have no idea what circumstances led to Jon's birth -- which, in a rare change of pace for "Game of Thrones," puts viewers on the same page as the readers of George R.R. Martin's book series. Martin, despite having written thousands of pages of Westros adventure, has not yet confirmed Jon Snow's parentage either in print or on screen. Fans have their theories, but the secret at this point could as easily die with Martin as it did with Ned.

"Breaking Bad": Walt let Jane die.

Bryan Cranston in 'Breaking Bad'
Ursula Coyote/AMC Bryan Cranston in 'Breaking Bad'

Walter White sat on this so long, we honestly thought it would never come out. When the drug kingpin stood over his partner's drug-addicted girlfriend and watched her choke to death on her own vomit, theoretically to preserve Jesse, it seemed inconceivable he would ever be able to admit to it. The act was so vile, it demanded to be kept a secret. How could anyone break so bad as to not only allow it to happen, but to then be found out (especially when there was no way for anyone else to stumble across the truth)?

Well, no one stumbled across the truth -- Walter told Jesse what he'd done, right to his face. Torn apart by the death of his brother-in-law Hank, Walter exacts his revenge on his now permanently ex-partner by exposing the one secret he knows will destroy him, and it does. Jesse may have never recovered from Heisenberg's most heinous secret, even though he lived to tell someone else the tale.

[Liz Shannon Miller and Ben Travers contributed to this list.]

Indiewire has partnered with WGN America and its new series "Manhattan." Set against the backdrop of the greatest race against time in the history of science — the mission to build the world's first atomic bomb — "Manhattan" follows the brilliant but flawed scientists and their families in Los Alamos as they attempt to coexist in a world where secrets and lies infiltrate every aspect of their lives. The Manhattan Project was so classified Vice President Harry Truman didn’t find out about the project until he was sworn in as President following FDR’s death. The series debuts this Sunday, July 27, 2014 -- find out more here.