In case the title didn't make it clear, major spoilers in here. If you haven't seen Once Upon a Time and want to watch it, don't read!
For those of you who do not watch Once Upon a Time (OUaT), the basic idea is that the evil queen from Snow White (Regina) banished the fairy tale characters to the real world in Storybrooke, and Emma Swan, our heroine, is the only one who can make them all remember who they are. As the story goes, the fairy tales we "know" are changed and fleshed out; our prince is really a shepherd in disguise, Little Red Riding Hood is actually the wolf herself, Cinderella got to the ball from an evil fairy, and Rumpelstiltskin ends up being the Beast from Beauty and the Beast. Let's focus on that last one.
Belle is presented initially like she is in the Disney movie. She volunteers to stay to save her family and in the process becomes the Beast's slave/servant/awkward sexual interest. And, just like in the Disney movie, we learn Rumpel is really just a good guy that can be saved! Belle is his savior! She can change him!
Well, kind of.
To its credit, OUaT does not take the literal physical transformation route. Rumpel has shiny gold skin and creepy eyes in fairy tale land, and he doesn't lose that when they fall in love and become the clean Mr. Gold–like character he is in the real world. In fact, Belle is taken away from him and locked in a tower by Regina, and we see very little of her until we find out she's been locked in an insane asylum in Storybrooke. But in the second season, we get a lot more of her, and we see a good deal of the relationship between Belle and Rumpel.
Initially, in fairy tale land, Belle is the loving companion figure of Disney. She "sees the good in everyone" and that is her overwhelming characteristic (when Ruby thinks she is going to turn into a wolf again, Belle says "rehabilitation is kind of my specialty"). She exists as a figure in relation to Rumpel—to show him his good side and remind him to be better. She is his pretty, reading servant who makes the dark figure redeemable, and we see her primarily in relation to him. I'll also give OUaT credit in that they did not make her a simpering, accepting little twit in an abusive relationship, but really her insistence that she can change him is disturbing. Rumpel is the beast character; he is defined by his surly attitude and gross mannerisms. Later in the second season, we learn she had to clean blood off aprons as he skinned Robin Hood for stealing a wand. Yet she stays. I could go on the expected rant about this, but I want to move on.
In Storybrooke, things start to change. After being freed from the asylum, Belle is initially repulsed by Rumpel's addiction to magic. She begs him to stop, and when he does not, she leaves him. He gives her a library as an apology and a way for her to have independence, and they start again. I still had some issues with this. She only gets independence from him, not on her own, and instead of spending any time alone, she agrees to start a relationship again with him. But, more importantly, Belle had an ameliorating effect on Rumpel. He wanted to be less of a dark being, and she saw the good in him once more. He needed this, and their relationship was almost endearing in a way. We still had the traditional dynamic, though. Rumpel was our salvageable, dark hero and Belle the stable good woman who makes him better. Yawn.
Halfway through the second season, Belle loses her memory (long story, curse, and fake human life) and becomes Lacey, an alcoholic barfly who dresses scandalously and likes to bring out the bad in our Rumpel. Rumpel degenerates, and they become the evil dark superstar couple. This is where I felt that it was clear their relationship had changed.
When Belle was gone, Rumpel really did begin to fall apart. In a way, Belle has more power over him than the story really allowed before. In addition to being his moral compass, Belle became his reason for living a good life. Though Rumpel always claims he is looking for his son, it is Belle that gives him the strength to do so. When his son rejects him, Belle is still there. In addition, the flashbacks during the season show Belle not as the servant with the good heart, but a character more dynamic than Disney would allow. She uses knowledge to track down a mythical beast with Mulan and save the country, and she releases Robin Hood from being a prisoner at her own peril. She proves she won't stay with Rumpel on his terms, but hers as well.
I do take issue that she's still primarily defined by her relationship, but I think that OUaT has done some rather interesting things with one of the most disturbing of Disney princesses. When Belle is good, Rumpel is good; when she's bad, he's bad. She's not just his barometer, but the wind itself that pushes him to either his salvation or his doom.
At the end of the second season, Rumpel leaves to help find his grandson, knowing he will probably die. Belle is left, but in her hand she holds instructions to save the town. While secondary, she has carved out her own power and is left in charge of a town of people. Not bad for the annoying girl whose only quality is seeing the good in others.