Just about everything that Dinky Doo does, but especially Chapter 5, "Catharsis," of Family Matters, when we finally get to see Sparkler's side of things, and when she and Dinky just break down in front of each other and Dinky ends up consoling her older half-sister.
And chapter six, where Sparkler and Ditzy begin reconciliation.
In Chapter 3 of Family Matters, Diamond Tiara actually compliments Dinky on all the hard work she did to earn money for her mother's birthday present. Sure, she tells her not to let anypony else know about it, but it's still a nice sentiment, especially if one sees it as a sign her father really is managing to teach his Spoiled Little Princess the value of hard work in some way...
Trixie not wanting to interrupt when Ditzy and Dinky are having a moment of peace in The Night After
The various ponies Carrot Top had helped out returning the favor to her in Carrot Top Season.
During Symphony for Moon and Sun, Lyra's absolute refusal to abandon her friend Octavia, despite her previous betrayal.
As an extension of that, while Octavia is being mind controlled into feeling worthless, what snaps her out of it is the mere idea that Lyra would abandon her. She knows that would never happen.
Luna comforting a crying Cadence in An Early Reunion. Becomes even more Heartwarming In Hindsight when you read the following chapter.
Cheerilee singing Ditzy a lullaby in Through the Fire and Flames after the poor girl blamed herself for letting her claustrophobia cause a setback to rescuing Trixie.
Scootaloo getting to meet members of the Guard who knew her mother in Foaling Around.
Luna and Trixie comforting each other in At the Grand Galloping Gala after the latter's Heroic BSOD. As rocky as their relationship is sometimes, it shows just how much they actually care about each other.
Later, the other Elements of Harmony all agree to help Trixie with her plan to force reform on the Night Court, even though it's made clear that what she intends to do is very illegal. Whatever the personal consequences will be for them, they barely hesitate to go to the firewall for each other and for the good of Equestria.
Lunaverse-Luna and Celestia (No, not Corona) wing-hugging in Crisis On Two Equestrias. Doubles as Tear Jerker with this line, though:
Celestia looked uncomfortable as she managed to get herself into a sitting position. “Princess Luna,” she said. “I am not your sister.”
“I know…” Luna breathed, not moving. “I know, but please, just for a moment…let me pretend…”
