The first scene: you can just feel the love Ariel has for Melody.
It's a quick moment, but there are a couple of toys in baby Melody's mobile. What are they? Wood carving toys of Sebastian and Flounder.
Baby Melody in general. You can't stop squealing about her cuteness.
Sebastian smiling warmly at baby Melody when she holds out her arms in his direction.
All of Ariel's sisters came to their niece's introduction for her christening.
Triton creating a rainbow with his trident after seeing Melody for the first time, smiling for joy at the sight of his granddaughter. He also makes a rainbow at the end of the movie after both humans and merfolk reunite.
The family's reconciliation near the end of the movie.
Melody: I'm sorry, Mother.
Ariel: Oh no, sweetie, we're sorry. We should've told you the truth.
Then Triton just comes and adds more of the heartwarmingness.
Triton: Just like your mother.
To top it all off, Melody runs to him and embraces him as her grandfather for the first time.
A subtle one, but when Triton gives Melody a choice to become a mermaid permanently in Atlantica, look closely at her parents' faces. They are understandably shocked because, after all, that means their beloved only child would be living somewhere else at a young age. However, they then show faces of support for their daughter. So, while they would clearly prefer that Triton wait until Melody was grown up to offer her that choice, they will still respect whatever choice she makes.
Although he was assigned by Triton without being consulted first, Sebastian seems to view Melody like the granddaughter he never had. He’s willing to listen to her when she’s having difficulty with her mother, and he tries to cheer her up after having a fight with Ariel.
Triton giving Melody the locket, so she'll always have a part of the sea with her.
The ending of the movie, where the mermaids and humans unite, and Melody is on her way to making lots of friends. She even offers a second chance to the kids who were rude to her at her birthday party, which they accept.
In her duet with her daughter, Ariel sings that when she finds Melody, she will hold her close and sing the song of the sea with her.
There's also a brief moment wherein we can see Ariel in her old grotto, which Triton likely rebuilt after the last movie's events.
Melody's enthusiasm at being a mermaid.
Ariel and Flounder reuniting after twelve years, which is followed by Flounder (with no hesitation) agreeing to help his best friend find her missing daughter.
Even though it was short, Melody's interactions with the merboy Alex can be described with one word: Adorkable.
When he introduces his two friends to "Mel-Mel", they both immediately take a liking to her, with one asking if she wants to hang out with them.
Melody and Alex meet again near the end of the movie in the same manner of accidentally bumping into each other. They remember each other, greet each other warmly, and shyly smile at one another.
