Stepsisters in storytelling often get a bad rap. This obviously comes from the plethora of fairy tales painting them as petty, vindictive brats. The movies inspired by these tales stick with that image, thus reinforcing the malicious stereotype. Not all films fall into this trap, though.
Some screenwriters portray stepsisters in a more favorable light. They may not be the spoiled children that the old tales make them out to be. They may even help the heroes in their quest. Granted, these characters are few and far between, but that ultimate helps them stand out.
5 Doris - The Shrek Series
The Shrek films lampoon fairy tales across the board, so it was only a matter of time before they tackled Cinderella. In Shrek 2, the heroine's "ugly stepsister" runs a seedy bar populated by disgruntled villains. She knows their dissatisfaction and, thus, is willing to listen to their troubles like the best bartenders. That policy even extends to the heroes when they come here in sadness. It's ironic since she doesn't exactly have the soothing pipes that one would expect. Instead, Larry King's voice comes out of her mouth.
The filmmakers knew that was comedic gold since they brought the character back for the (albeit inferior) sequel. In Shrek the Third, Doris helps Fiona and the other princesses fight against Prince Charming's thugs. She's not only emotionally supportive during the baby shower and other social events, but she brings some much-needed muscle to the fights. She's actually more useful than Cinderella. Granted, that's not saying a lot. She and the other princesses are dead weight here, but the compliment still stands.
4 Kimi - Rugrats In Paris
Chucky was always different from the other Rugrats in his home life. They each had two parents, but he only had his dad. Thankfully, that changes during the second movie: Rugrats in Paris. On a trip to a Japanese-themed amusement park, the gang meets Kimi, daughter of the park administrator's assistant. She's only too happy to venture through the park and aid the other babies, as she's equal parts daring and selfless.
That proves ideal once Chucky's dad marries her mom. She proves a constant companion for the four-eyed 'fraidy-cat. Her intrepid and loving nature bring him out of his shell more than the other characters ever could. At the same time, she's mindful of his vulnerabilities. These traits make Kimi a welcome addition to both his family and the Rugrats team.
3 Mel - Ever After: A Cinderella Story
Though one of the countless Cinderella adaptations, Ever After throws a few curveballs into its narrative. Most noticeable is the fact that only one of the heroine's stepsisters is wicked; the other is sympathetic to her plight. She even tends to her wounds after the evil stepmother has her whipped. In a life of misery, it's undoubtedly a relief to have a friendly face to lessen the hardship.
This culminates in her playing an instrumental part in securing her sister's happily ever after. When the stepmother sells Cinderella off, Mel informs the prince. She risks her own life of luxury in doing so, making her action more admirable. No wonder karma spares her in the end.
2 Nebula - The Marvel Cinematic Universe
This Marvel cyborg's relationship with Gamora doesn't start out on the best foot. They begin their journey in Guardians of the Galaxy as fierce rivals, with Nebula trying to kill her sister on several occasions. However, that hostility fades once her green-skinned sibling spares her life. What's more is that Nebula feels indebted once Thanos makes them both pawns in his larger MCU schemes.
As a result, she demonstrates fierce devotion in redeeming herself. She goes back in time and challenges a galactic menace to bring her sister back to life. Most siblings, biological or otherwise, can only dream of that kind of dedication. Granted, that tireless energy likely stems from being a robot, but her connection with Gamora is unmistakably human (at least as far as alien cyborgs go). One couldn't ask for a better combination, as she will always have your back.
1 Rory - Gilmore Girls: A Year In The Life
Rory Gilmore spends most of her life as an only child. In the Gilmore Girls TV show, this leaves her in an awkward place whenever her mom, Lorelai, dates someone new. Not only must she acquaint herself with a total stranger, but she has no sibling or anyone else who can relate to her problem. That doesn't seem to be an issue once Lorelai grows closer to Luke, the local diner owner and longtime friend. He's practically family already. Unfortunately, that all changes when Luke's daughter, April, shows up out of nowhere and throws a monkey wrench in the whole situation.
Fast-forward to the revival films--A Year in the Life--and Lorelai and Luke get married. This obviously makes Rory and April stepsisters: an outcome that definitely benefits the latter. Viewers know that Rory is the most altruistic person in town. Accommodating to a fault, she goes to great lengths to help those who ask for it. She demonstrates this in the films by letting April unload all her insecurities without a word of protest, and she'll likely continue to be that approachable sibling in the future.