In chapter four Brownie manages to reunite Applejack, Rarity, Fluttershy, Rainbow Dash and Pinkie Pie during Twilight's absence since she turned as a Princess. Doubles as a Crowning Moment of Awesome.
When Brownie falls ill at the end of chapter five/start ofchapter six, Rainbow Dash stays in his house to take care of him. This lasts for about three straight days.
Later, in chapter eight, Rainbow Dash occupies the only bed and tells Brownie to sleep in Spike's basket. Just as he's about to search for a couch, she allows him to share the bed with her as long as he doesn't try anything funny. Mind you, she's still angry at this point, but it's still heartwarming.
And a bit later, Brownie finally makes a love confession about why he developed a crush on Rainbow Dash. This earns him a second chance to set everything right.
At the end of the story, Rainbow Dash delivers a "Shut Up" Kiss to Brownie.
Rainbow Dash: Shut up and kiss me.
Through The Prism
Brownie finally loses his virginity as Rainbow Dash helps and guides him through the entire process, teaching him how to do it properly. The entire fic is full of these moments.
At the start of the story, there's a mention about how Rainbow Dash felt too overhelmed with Brownie's presence before he explained that since his family is too far away, and since he never had a marefriend before, she's the only one he can pour his love and dedication. This confession made Rainbow Dash realize how lucky she was to have Brownie as her coltfriend.