Elinor changing back into her human self at the end of the film. Especially the royal family group hug afterwards. And the clans looking on surprised and happy to see the queen again.
The way she repeatedly kisses her daughter is pretty sweet as well.
Elinor realizing that forcing Merida into marriage is wrong, and allowing her to back out and get married if and when she chooses.
And Merida's own actions in that scene — she's totally willing to make a sacrifice and do what has to be done to save her mother and prevent another war, but as soon as that's not 100% necessary she finds a peaceful and suitable solution that not only gives her what she wants but gives her suitors what they've really wanted also. They're every bit as reluctant as she is, so her getting rid of official marriages of alliance isn't surly teenage rebellion — it's her first act as a prudent future ruler to break from tradition so the kingdom can grow and progress.
The lords finally coming around to the decision to respect their sons' wishes, with all three respectfully bowing to Merida.
Elinor and Fergus's marriage is a Crowning Relationship of Heartwarming. Despite the fact that it was an arranged marriage, it's a very, veryhappy one.
Every time Merida is in danger, Bear!Elinor always reaches out to protect her; i.e., when she saw her own shadow and thought there was a bear in the room, she immediately flung an arm out to protect Merida. When the witch's cottage collapses, she embraces Merida to protect her from the debris. And then there's the literal exhibition of the Mama Bear trope when Bear!Elinor goes completely berserk on Mor'du after it threatened Merida.
There's a new tapestry. One that shows Bear!Elinor and Merida holding hands.
The spirit of the prince who became Mordu, rising from the now crushed body of the bear, nods in thanks to Elinor and Merida for freeing him from his curse.
The entire movie itself is considered heartwarming when it's about reconciliation.
During the departure scene of the three clans, we see the big scary scar covered warrior of the Dingwall clan clearly being romantic with the small plump maid.
During the final battle, there's an almost Freeze-Frame Bonus of young Macintosh worriedly helping his father up off the ground. Considering the fact that his character is originally portrayed as arrogant and full of himself, it's a peek at the real person under all that competitiveness.
At the beginning, Merida's free day. You know you just feel like a kid again after watching it.
When war is imminent between the four clans, one of them orders the king to choose one of their sons to marry Merida.
Fergus:NONE OF YOUR SONS ARE FIT TO MARRY MY DAUGHTER!
Elinor trying to convince her triplet sons to eat their haggis. It just takes a parent or child back to those days.
Fergus giving a young Merida a bow for her birthday. This moment is particularly sweet considering the time period they are in and how it was considered "wrong" for girls to have weapons. But Fergus just wants his little girl to know how to fight.
During this time period, kings and queens would have tutors to teach their heirs. But, Elinor doesn't do that. Even though Elinor crosses into a My Beloved Smother, she personally takes time to educate Merida on how to be a proper princess, later queen.
During the montage of Elinor teaching Merida how to be a Proper Lady, she at one points said "[a princess] must be cautious". We don't the exact details, but seeing Elinor reach out to Merida reminds any child or parent about the latter always looking out for the former.
Following Merida's speech about choosing one's own fate, Young MacGuffin's says "It's not fair making us fight for the hand of a quine who doesn't want any bit of it!" Compared to Young Macintosh and Wee Dingwall, who speak of making their own choices, MacGuffin lets his father know he cares about everyone's feelings on the matter. He really is such a Nice Guy!
Brenda Chapman's inspiration for the story is her relationship with her daughter.