"ACTING NICE IS A CHILDISH PROFESSION - PRETENDING YOU'RE SOMEONE ELSE, AND AT THE SAME TIME, SELLING YOURSELF."
Watching the fall, for lack of a better term, of Nadeko Sengoku is fascinating. It runs parallel to the cliched response upon seeing a trainwreck - "I simply could not look away! It was awful! Let me tell you how awful it was in gory detail!" - with an added air of delight. Typically, when we watch our idols "fall," be them the quiet, pretty, girl-next-door, or the latest and greatest in pop music, there is an air of superiority that we're encouraged to feel while watching the entire event.
Yet, I did not feel superior to Nadeko watching her cavort in a pool of blood. I was rooting for her. I wanted her to destroy everything.
Pre-transformation Nadeko is your anime-standard junior high school student. Her initial arc in Bakemonogatari was the least appealing, both in visuals and in story. There wasn't anything particularly wrong with Nadeko - the major criticisms that are levied against her are that she's polite and boring, or that Bakemonogatari takes advantage of her oddity to - but there certainly wasn't anything interesting about her. She was a cute girl with a cute voice actress and a cute opening song, embodying the girlish nature of a childhood crush. Her time spent onscreen in both Bakemonogatari and Nisemonogatari is clothed in doll-like outfits, specifically designed to appeal to her false "big brother," Koyomi Araragi, within the narrative, and a certain viewing demographic outside of it.
As Kuchinawa - who is also Nadeko herself - Ougi, and Shinobu all point out, Nadeko's niceness is thoroughly disingenuous. She is selling a specific image of herself. Additionally, the series is also selling Nadeko to us, the viewer. After all, who among us did not sway their heads, or hum along to "Ren'ai Circulation?" Even if Nadeko was boring, at least she was cute to watch.
Pigeonholed into this role by both the viewing audience, and characters in-universe, Monogatari Second Season reveals that Nadeko has, unwittingly or not, taken advantage of this position. When faced with not only Araragi's rejection of her, but what her privilege has afforded her in life, Nadeko breaks. Unable to admit that she has received special treatment due to her looks, Nadeko also does not fully reject this idea. She still wants to play the role of damsel in distress, waiting for Araragi to save her, even when she actively encourages and invites a supernatural oddity upon herself. She berates her classmates for their inability to get over their own petty squabbles, but cannot face the fact that Araragi has a girlfriend.
With her insular and selfish ideas of romanticism, Nadeko can also be seen as an insert for budding adolescence. She is not in love with Araragi, but she's certainly in love with the idea of being in love with someone. Araragi is a safe choice for Nadeko - even with the series constant reminders of his, and our own, perversion - as Monogatari makes it clear that he is uninterested in her romantically. This way, Nadeko is able to pine for his comfort without the emotional honesty required of an adult relationship. Placing Nadeko into this specific framework is not ; however, and there's certainly still a nasty thread of crazed teenaged girl in her actions. That being said, Monogatari goes between playing up Nadeko's presumed craziness, and outlining the path traveled from polite student to enraged snake goddess (hint: both the in-universe characters and the viewing audience are involved).
"DON'T YOU GET IT? THERE IS NOTHING YOU CAN DO FOR THAT GIRL. IF YOU'RE AROUND, THAT GIRL WILL JUST BE USELESS."
-Deishu Kaiki to Koyomi Araragi, Monogatari Second Season, episode 26
Nadeko is eventually swayed back to reality not by mollifying words from those she claims to care about, but known con-artist turned anti-hero, Deishu Kaiki. Kaiki appeals to her humanity, laying bare the reality of what she could do as a human as opposed to being trapped within her vengeful mindset as a goddess. Of all things, it is her talent in the arts and hereto unknown desire to become a manga artist that resonates with Nadeko emotionally. If she fails at that, Kaiki claims, there are so many other things that she will be able to do as a human. If there's one thing that people are good at, it's constantly reinventing themselves.
At the end of her ordeal, Araragi arrives fashionably late in both his physical presence at the temple, and his mindset regarding Nadeko. Upon seeing Kaiki with Nadeko, he immediately moves to rescue Nadeko. This instinctive reaction from Araragi piqued an optimistic response from me as a viewer. In spite of Kaiki's words that Nadeko will be useless because of Araragi's presence - presumably due to her romantic interest in him - there's a hint that Araragi cannot help her because of who he is at that moment: a person thoroughly stuck in the past, unable to see Nadeko as anything other than his somewhat fetishized false younger sister. As a key player in pigeonholing Nadeko - regardless of whether she took specific advantage of her role or not - Araragi will forever be unable to provide any true support to her if he does not change the way he views her.
If disallowed from destroying everything as a goddess, I want for the now-human Nadeko to reinvent herself once more. Not as the paragon of a girlish love, and not as an alcoholic Medusa, but as whatever, or whoever she wishes to be. Although, I have to admit, the Nadeko that screamed at her classmates for being idiots was amazing.