Mia dumping her ice cream cone all over Lana’s cheerleading outfit after Lana insults Tina.
Before that, her standing up to Lilly (for the first time in her life) for insulting her after she gets a makeover.
Phillipe helping Helen and Mr. Gianini elope to Mexico and avoid the tawdry, expensive Shotgun Wedding that his mother Clarisse has arranged.
Michael telling off Lilly for harassing Mia about being a Princess in the first book, showing the amount of knowledge he has of the Genovian government and its history and noting that Mia's father is the opposite of a Upper-Class Twit; later calls out Lilly as being jealous of Mia for changing her hair, being a princess, and for getting a new friend and calls her vain.
Pardon me, Lilly, but it's my understanding that Mia's father works extremely hard for his country. His father's historic pledge, after Mussolini's forces invaded in 1939, to exercise the rights of sovereignty in accordance with the political and economic interests of neighboring France in exchange for military and naval protection in the event of war might have tied the hands of a lesser politician, but Mia's father has managed to work around that agreement. His efforts have resulted in a nation that has the highest literacy rate in Europe, some of the best educational attainment rates, and the lowest infant mortality, inflation, and unemployment rates in the Western Hemisphere.
Grandmere smacking the "Blind Guy" after helping to escort him across the street and revealing him to possess great eyesight.
Mia ripping Lana's (fake, but she didn't know that) braid off for calling Perin a hermaphrodite.
Mia's speech when she runs for student body president.
Lana even later acknowledges it was an awesome speech, and in book 9 recommends Mia to speak to the Domina Rei. Mia kicks it out of the park with her speech about Princess Amelie, a sixteen-year old princess who ruled during the Black Plague, saved lives despite her uncle attempting to usurp the throne and burn her proclamations, and mandated that Genovia become a constitutional monarchy in her last proclamation.
An Off Screen Moment Of Awesome, but Michael telling Lilly to be nice to Mia after Lilly created the hate website. This probably spurred Lilly's attitude as The Atoner in book 10.
Mia becoming a published novelist at the age of eighteen.
Olivia leaving her aunt and her family to live with Mia and their father. Even better was "The Reason You Suck" Speech she launches on her aunt for restricting her life, stealing the money meant for her, and for caring more about her carpet than her bleeding niece:
No! Of course not! I don't want to live with you because all you cared about when I walked in was getting the stain out of your stupid carpet. They cared about what happened to me. That's why I want to go live with them.
Grandmere's Death Glare aimed at Olivia's Uncle when he objects to the girl having a dog, due to his allergies, given that he's a huge bully that aligns himself with other bullies and is raising kids a lot like him, it's quite awesome to see him cowed by just a look from her.
It's revealed in Olivia's book that Genovia is suing her bully's father, a lawyer who basically lets his daughter get away with murder by threatening litigation against their private school; that girl and her father are no longer a Karma Houdini pair.
In the second-to-last book, Lana being mature enough to bury the hatchet with Mia (and, for that matter, Mia agreeing despite what Lana has put her through). She's still sometimes a shallow Alpha Bitch but she realises that their feud was childish and they gain a pretty good friendship instead of continuing to fight.
Mia's story of how she and Lilly bonded in first grade, when a boy dropped his trousers in front of her and Mia in the music room.
She just looked Orville straight in the eye and said, “I’ve seen bigger.” And you know what? Orville never did it again.
Philippe doing what he didn't do the first time around and abdicating the throne for a second chance with Helen in A Royal Wedding.
From the films:
Mia smears Lana with an ice cream cone and ruins her outfit due to Lana being a bitch to her (as usual). Lana tries to whine and play the victim to Ms. Gupta, only for Ms. Gupta to sarcastically say that she was in a meeting and she can "send her uniform to dry cleaning."
Notably, Mia didn't cone Lana because Lana was harassing her. She only did that after Lana started mocking Jeremiah who, for all his weirdness, is one of the people that's actually nice to Mia. Mia wasn't going to take that sitting down.
Mia using a baseball bat to hit a baseball so hard, it hits Josh in the groin.
Mia gets fed up with Lily self-rightously mocking and lecturing her post-makeover and tells her to shut up.
Mia: Lily-! Just- stop it, okay?! Just because your hair sucks, get off mine!
Clarisse talking Mia out of getting taken downtown after the car accident - which the cops were admittedly going a bit far on. She employs complete Refuge in Audacity by trying to flatter the cops into thinking they're getting knighted for upholding the law so well, and they're so humbled they instantly let Mia off. Bonus points for Mia being very quick on the uptake when Clarisse starts her thing.
Mia: You are the coolest Queen ever.
Clarisse: All in a day's work.
A small moment for Clarisse. When she arrives at the high school the day Mia has been outed, a reporter shoves his microphone in her face for a question. She calmly and classily takes the microphone and puts it in his pocket without saying a word.
Joe calling Clarisse on how she's being treating Mia after she was literally humiliated by her peers, regardless of how she embarrassed the royal family.
Clarisse: You're saying that as a Queen I was too harsh on her? Joe: I'm saying that as a grandmother, you may have been too harsh on your granddaughter.
Even better, the second movie shows that Clarisse has taken Joe's point to heart, as she makes more of a distinction between her relationship to Mia as her queen versus their relationship as grandmother and granddaughter.
Clarisse: As your queen I cannot condone it, as your grandmother I say right on.
Ms. Harbula coming to Mia's aid when she gets surprised by paparazzi in her towel.
She and Principal Gupta getting Mia safely indoors when her princess status is made public and physically separating her from the crowd of paparazzi.
Mia, Helen and Clarissa being able to calmly discuss the situation after Mia's identity gets leaked shows a lot of Character Development since their last discussion, shortly after Mia was told she was a princess. Whereas before Mia was completely opposed to becoming a princess, here she decides to stick with princess lessons and see it through before she makes her final decision.
