Mia and Rocky's relationship; she adores her kid half-brother.
Also, surprisingly, Rocky adores ''Grandmere'' and keeps asking for kisses from her. Grandmere apparently returns the affection for her step-grandson, who isn't even related to her.
After Mr. Giannini dies, Rocky starts acting out by talking about farts, asteroids and volcanoes. Philippe acts as a Reasonable Authority Figure about Rocky acting up, even saying he qualifies for a gifted program in Genovia, if Helen and Rocky will move with him there.
Every interaction that Mia has with her half-sister Olivia when they aren't in Tear Jerker territory. Olivia with her Cheerful Child nature inspires this in Mia and even Grandmere.
To mark the point, Olivia wins over Grandmere, who was against revealing her, by commenting on how she loves poodles and thinks that they are the smartest dog breed available. A bond instantly forms over the two.
Philippe's interactions with his second daughter are also darling, up to and including his massive Papa Wolf moment when the people he thought he could trust to care for Olivia either ignore or take amusement from her being mistreated and the culprit being in a position to pull a Karma Houdini.
Joe, after discreetly noticing the jealous Lilly mocking Mia's new hairdo/makeover, asks her privately about her tears, then reminds her:
Joe: No one can make you feel inferior without your consent.
Mia: Eleanor Roosevelt said that.
Joe: Another special lady, like yourself.
At a state dinner, her first public appearance, Mia takes too much sorbet, gets an ice cream headache, and begins to flail wildly. The guests next to her (the prime minister and his wife!) realize what is going on and give themselves ice cream headaches to take the spotlight off Mia.
What makes this sweeter is that they do this even as Mia tries to tell them not to embarrass themselves.
Lilly's heartfelt speech to Mia to try and convince her to be a princess.
Mia's letter from her father.
"Because you saw me when I was invisible."
After a botched routine surgery on Julie Andrews' vocal cords tragically robbed her of her amazing vocal range, it seemed that Andrews would never sing again. But The Princess Diaries 2: Royal Engagement changed all that, when she was given "Your Crowning Glory", a song deliberately written as easy for Andrews to sing. Hearing her in a Disney film singing this simple, yet beautiful song and gaining the confidence to sing in public once more certainly qualifies this as a CMOH.
When Andrews sang it live on the film set during shooting, the film crew were in tears.
The scene with the girls from the orphanage in the second film definitely counts.
Mia: And I say that anyone can be a princess today.
Nicholas' change of heart. To stop Mia from entering a loveless political marriage and ensure that she can become queen in her own right regardless by abdicating, he takes his grandfather's penny farthing bicycle, trades it with a farmer for his horse, arrives just in time at the church in support of Mia to give a heartwarming and persuasive speech to the parliament. And all topped off with:
Nicholas: And, besides... [looks directly at Mia] Just think how lovely she'll look on our postage stamp.
How do you completely sell an utterly cliche chick-flick romance? You cast the incredibly talented Anne Hathaway and Chris Pine, sit back, and let them sell it for you. Their whole relationship is too adorable for words, and it's all because they made it genuine.
The ending of the second movie where "the sparrow takes off" and "the eagle flies for the last time". Not only is it awesome to see Mia finally crowned as queen, but almost everyone from throughout the movie, even those who had seemingly been against her or at least to enjoy her misfortunes are all there and happily join in on the Genovian national anthem, from Nicholas and the stoic new secret service agent, to her ex-fiance and his love interest, to the annoying Scottish gossip-rag journalist, even the scheming nobles from the first movie- and a song that was mostly Played for Laughs in the first movie becomes a sincere, heartfelt, even stirring performance.
Mia and Lilly's talk on the roof.
Lilly: Wanting to rock the world and having zip power like me, that's a nightmare. But you being a princess is just... wow. Mia: Okay, what is so "wow"? Lilly: "Wow" is having the power to affect change; make people listen! Do you know how many teenagers have that power?