The movie is really about Sweet Pea.
Everything that happens in the film is a reflection of the internal struggle of Sweet Pea, the catalyst for which is her being lobotomized.
And for the sake of clarity, Zack Snyder was even kind enough to throw this kid into the mix. He first appears during the wartime fantasy scenario, and then again getting on the bus. Sweet Pea takes note of him both times, for no other reason than to tell you that NONE OF THIS IS REAL.
Baby Doll, meanwhile, is the physical embodiment of Sweet Pea — a sad, pouty-lipped object of men’s affections and desires. She’s the “guardian angel” that Sweet Pea conjures up to deal with having a really **** life. That’s why she’s narrating the film instead of Baby Doll.
So all that stuff we see with Baby Doll during the first act of the film — that’s Sweet Pea acting out her past trauma in her mind, just as she was taught to do in the mental institution.
This is also why the film opens on a stage — a direct parallel to how Sweet Pea is acting out that same trauma on a stage when Baby Doll first arrives.
Then comes the lobotomy, which is the key to everything that happens in the film.
Reimagined through Baby Doll, Sweet Pea disassociates from reality just as that needle plunges into her brain, retreating into her mind in the same way she’s taught to by Dr. Gorski.
This is also what happened in Sweet Pea’s real life, and the effect of that lobotomy is… the movie.
Yep, Sucker Punch is the result of a lobotomy — just one big, weird subconscious coping mechanism for a girl to find peace in spite of the tragedy that’s befallen her.
This time around though, Sweet Pea is able to interrupt the lobotomy, intruding on her own story. She’s even able to repurpose the accidental killing of her sister into a deliberate and necessary sacrifice on her sister’s part to save her.
And here’s where things get meta.
In this second layer of fantasy, Sweet Pea imagines herself and the rest of the girls working in a brothel, objectified and lusted after by an audience in the most overt manner possible.
This mirrors us — the actual audience — tuning in to see these girls perform for us in skimpy school girl outfits and tight leather and other assorted smutty get-ups.
This connection is made clear from the film’s very first scene, which lets us know that we’re the audience watching all this unfold on stage. By choosing to watch the movie, we are complicit in everything that’s happening.