It has a startling tendency to turn all your characters more or less into you. Particularly on a moral plane. I still remember the con panel where one panelist could devise only the noblest of motives for murder, and the other only desperate ones -- I observed this and suggested that a look at actual murderers might help some -- which the second panelist, I kid you not, called a cop-out.
Still, it can be a wrestle. Patricia C. Wrede was writing about multiple viewpoints, and discussed writing "Cinderella" from the stepmother's.
For the straightforward one, Cinderella, her godmother, and the prince are the obvious main choices; the evil stepsisters and stepmother could be viewpoints, but if they are, they’ll almost have to be one-note caricatures in order to keep the storyline the same. Most authors don’t try; if they want more viewpoints, they go for original characters whose presence is implied by the setting – palace footmen, the king and queen, servants, townsfolk.
A complex retelling, on the other hand, almost requires the stepsisters and the stepmother’s viewpoints as well as Cinderella’s, and not as caricatures, either – as individuals who have a different take on what is going on, and good reasons for what they do that the reader would never know about without those viewpoints. Perhaps the stepmother is being blackmailed and that’s why money is so tight, or perhaps she’s trying to fend off a skeevy old rich dude who wants to buy all three of the girls for his harem. Maybe the stepsisters are running a charity fundraising business that Cinderella made a nasty comment about once (not knowing they were involved). Maybe the stepmom has cancer, unknown to Cinderella, and is trying to get her family safely settled before she dies. Maybe the chores she sets Cinderella aren’t really so bad if one looks at them from a different viewpoint (I certainly thought that I was much-put-upon when I was sixteen and had to do dishes and fold laundry).
You notice that all the reasons she offers are "good reasons" not only in the aesthetic sense that they make the stepmother more complex and human, but the moral sense of making her a better, even good, person.
I commented on that at the time, and suggested
She and Cinderella’s father were an arranged match until he fell in love and married Cinderella’s mother, and she’s out for revenge — both in abusing Cinderella and in getting an even grander match for her daughters.
She’s after Cinderella’s inheritance; there’s only so much to go around, after all, and she doesn’t have much for her daughters’ dowries.
She suffered a painful decline in status in marrying a merchant, and is determined to crawl her way back up the social ladder. Perhaps she has relatives who took the money resulting from the union to get themselves far more respectable positions, and who do not treat her as an equal. (How much sympathy this will garner depends on how much honest poverty she was warding off. Or perhaps she just didn’t want to buckle down to a budget and careful management of the family estate — how many alternative she has also matters.)
Whereupon the muse saw a chance to play and did. What if the father and stepmother had been the love match, forcibly broken up for an arranged marriage by her parents, whereupon he submitted to a marriage to a quiet, dowdy merchant's daughter instead of his passionate, fiery true love? And she's using Cinderella as a butt for her rage when her true love is snatched from her when she finally managed to marry him, after so many years? Hmm. Perhaps -- perhaps even their snatch at love in middle age was tainted by his realization that he had loved his first wife for her gentleness, patience, and -- thrift. She was a wealthy merchant's daughter, and having money didn't go to her head. (She even insisted that Cinderella know all about managing a household, just in case, and Ella was inspecting something about the fireplaces when her father surprised her with his new wife, and hence the title Cinder got attached.) The stepmother, daughter of a poor noble and widow of another, acts as if money will never run dry, because he's rich. She only realized the problem when she was widowed again, and also learned that Cinderella's mother's money is tied up for her, and the stepmother is using Cinderella as a servant both for cheapness, to keep in the income from her mother, and out of never admitted spite for her mother for winning the father's heart away, and her father for being won.
sigh. Not that the muse goes on from there. All that backstory, and all the muse suggests for the present day is that the stepmother is as cruel to the stepsisters in forcing them to ready themselves to win an appropriate husband.