Beehive Hairdo: After living the last few years in New York, Nellie has abandoned her signature Regal Ringlets for a beehive hairstyle.
Big Sister Instinct: Despite the bad impression Nancy left on her, Nellie still joins the search party when her adoptive little sister runs away and even talks to her parents about how Nancy must be feeling after the sister she was adopted to serve as a replacement for is back.
Book Ends: This is Nellie's final appearance, used to show how much she's grown and prove she's now a dear friend of Laura and not a jerk any longer.
Green-Eyed Monster: Nancy when Nellie starts getting everyone's attention.
I Just Want to Be Special: Nancy, all the way, when Nellie comes to town and more people are paying attention to her.
Redemption Promotion: Nellie seems to have hit the jackpot with her redemption. Not only is she Happily Married and running a sucessful business with Percival, but everyone is happy to see again when she visits Walnut Grove, (even Mr. Edwards, who didn't witness her change of heart and Willie, who used to see her as just a Big Sister Bully), at her birthday party everyone is genuinely happy with her (whereas people mostly seemed to tolerate her in childhood), and Sarah Carter writers an article in her newspaper about her trajectory, further cementing how much it paid off to change for the better... all of which pokes Nancy's jealousy.
Redemption Quest: It started at the end of the sixth season, and continued during the seventh, but Nellie completes the circle here from one-time Alpha Bitch to the mature, responsible, hard-working and successful woman that she would remain for the rest of her life. She is no longer smug about her upper-class background; she has empathy and is willing to be an example to others … everything that her mother is not. (Although it is clear she still loves her mother very dearly.)
Right for the Wrong Reasons: After Nancy runs away, Nellie starts realizing that her return is causing abandonment feelings to her adoptive little sister, who was adopted especifically to fill the void left by her absence to their mother, and that they should make it clear that she's more than a replacement for her older sister. Nellie is right about Nancy's feelings, but Nancy is still a rotten egg and her anger is mostly because no matter how much attention and care people give her, she'll never be satisfied and always be a jealous brat.
Series Continuity Error: Laura recalls the events of Season 4 episode "The Rivals", in which she put apples in her dress to attract a boy's attention. She says the boy was named Jeremy Dodds and that she and Nellie were competing for him, but the boy in the episode was Jimmy Hill, and Nellie not only wasn't interested in him, but actually gave Laura advice about how to get his attention (it backfired, but still).
Sizable Semitic Nose: Mentioned when Nellie is showing her parents pictures of her twins, Mrs. Oleson not so subtly worries about the size of their noses, thinking they're taking after their Jewish father. Nels responds that their noses look exactly like hers.
