Nightshade is a thestral who was transferred from the Lunar Guard to Twilight's royal guard. Like Scootaloo, he was an orphan. And that bond of understanding is why he adopts Scootaloo. Also like Scootaloo, he has issues that he has to work through. Though they are not the only ones with issues. Rainbow Dash also has her issues to work through as well, having secrets about her past that she is ashamed of.
Scootaloo is a pegasus filly who has trouble flying and is a member of the Cutie Mark Crusaders. Like Nightshade Scootaloo is an orphan. Though she has trust issues, that bond of understanding will perhaps be what helps break through her shell. But though she has her issues, she realizes that Nightshade also has issues. And she learns that holding in your feelings can be harmful.
Rainbow Dash is a pegasus who's the winner of the Best Young Fliers competition as well as being a Wonderbolt. On the surface, she is confident in herself. However, nopony can keep up a facade like that forever. And secrets about her past, and her bond with Scootaloo, are revealed. And those secrets may jeopardize her bond with Scootaloo. But those secrets, as painful as they may be, has to be explained to understand her reluctance to adopt Scootaloo herself.
[I didn't have any prereaders or editors for the first chapter. But Chapters 2 and up are preread by THMXTaylorLee. Anyone else who's willing to preread/edit are welcome to contact me.]