Sally Draper, played by Kiernan Shipka, in a “Mad Men” gallery image from Season 6. Credit: Frank Ockenfels/AMC

Sally Draper, played by Kiernan Shipka, is five-years-old when we’re first officially introduced to her. (That is, when she’s actually awake.) In the second episode of “Mad Men,” back in July of 2007, she’s playing a game of “spaceman” with her brother Billy, and her head is in a dry cleaning bag. Betty tells her: “If the clothes from that dry cleaning bag are on the floor of my closet, you’re going to be a very sorry young lady.” Sally sadly nods and runs away. In the beginning, Sally’s mainly there just to get reprimanded by her mom.

[Related: Hank Stuever reviews Season 7 of “Mad Men"]

Sally in Season 1. via madmenscreencaps

But over the past few seasons, “Mad Men’s” creator, Matthew Weiner, has been placing Sally in some of the show’s most pivotal scenes, and for good reason. Among its many themes, “Mad Men” is also a show about being a parent and how one’s childhood affects a person’s experience as a mother or father. Even as we’re watching Sally now, growing into her rebellious teenage years, we’re thinking of her as Betty 2.0 and the mistakes we all know she won’t be making. Like, for instance, telling her daughter that kissing a boy means the boy is taking something away from the girl.

“You don’t kiss boys, boys kiss you,” Betty says to her then nine-year-old daughter in that memorable scene.

Sally’s growing up and “Mad Men” is growing up with her.

Her adolescence has already told us a lot about Don. Take the Season 4 episode in which she sneaks into the Sterling Cooper Draper Pryce office because she wants to live with her father. That’s when Sally is shielded from Miss Blankenship’s corpse and tuned into Don’s mischievous personal life after meeting Faye and Megan in the office; it’s also where we see Don surprisingly take the next day off to spend time with his daughter.

We see him at his most tender around her, while he’s trying to explain to her what adulthood consists of. When she attends the Codfish Ball with Don, we see him get her a highly treasured Shirley Temple. Last season, when she walked in on her father and Sylvia mid-coitus, Don calmly explains that he was just “comforting Mrs. Rosen.” Never one to be fooled by her father’s philandering, she’s upset with him and in turn, Don takes her and her brothers to the rundown home he grew up in to give her a little more perspective. The look she gave him sort of said it all. Turns out, she knows more about Don’s work life and personal life than any other Draper on the show.

via fyeahmm

Even if she’s not technically the show’s secret protagonist just yet, she’s at least the most fun to watch. Since Sally is still considered a child, she’s given the most clearance to rebel and she certainly takes advantage of that. While most of the adults on “Mad Men” could be characterized as children trapped in adult bodies, Sally is unarguably an adult trapped in a child’s body and is willing to do anything to prove it.

Her rebellious tendencies have created some of the most entertaining scenes of “Mad Men’s” run so far, from Sally’s first cigarette in her mother’s bathroom to a very young Sally making her father a Tom Collins in Season 2. Then there’s that time she cut her own hair and was sent to therapy, and that time she was caught “touching herself” at a slumber party and then — unsurprisingly — sent to therapy yet again. And last season’s girls boarding school episode was particularly epic, with Sally turning down a boy and rebelling against a gang of bully girls.

We see her stumbling into adolescence — something almost everyone can relate to — and that’s helped make Sally the show’s sassiest character. She also has an impressive arsenal of biting one-liners.

A sampler:

Her exploratory nature has also given the show a lot of life, like when Sally walked in on Roger receiving oral sex from Megan’s mom, after which Glen asks her how the city was and she responds with one word: “Dirty.”

Because she’s young, she can mess up in a way that’s liberating for a show that’s quickly becoming excruciatingly even-keeled.

Without her, “Mad Men” would lose a lot of its sense of danger. We know that Sally is on a rebellious streak and because of her youth, the missteps she makes could have actual consequences. She’s not bolstered by a reputation, she’s just a girl trying to get by with two of the TV world’s worst parents.

Given last season’s complex Sally storylines, we can only hope for more Sally screen time in Season 7. Depending on the year the season is set in, Sally could be 15 or 16 or older which could make for juicy (imagined by me) plots like: Sally gets a prom dress. Or maybe she doesn’t go to prom — maybe she skips the dance to go to a Jimi Hendrix concert. Or, Sally gets her first real boyfriend (hopefully it’s not Glen) and has her first breakup but is still really cool about it. Or maybe she’s not and she slashes his tires and gets arrested.

In the remaining 14 episodes of “Mad Men”, lots of strange things could happen to Sally Draper but we can only hope that in the end she ends up happy, healthy and not married to Glen.