I might as well give you some more feedback up to date.
So far, you've done a really good job with keeping the mane 6's personalities accurate. I'm a little worried about how buddy buddy they are with Midnight, though. They're using nicknames... most of which the mane 6 don't use with each other, save for "Dashie", which is only used by Pinkie Pie, if I recall correctly... Maybe "Twi" used used by Applejack...
The other thing that bothers me is how... um... graphic the scene with the Ursa Minor is. I know you're objective was to injure Midnight, but I think you went a little overboard with how much explaining of his injuries you did. Then again, I'm a little weak and cringe at the slightest sign of discomfort. Just the mere mention of "bone against bone" makes me uneasy.
I would recommend using a more animated style of injuring Midnight, something less "real". Maybe something like Midnight getting swatted and sailing across the room in a sideways barrel roll. Just no open wounds or blood or bones snapping or shattering or... yeah.
On another note... I sense some indirect foreshadowing concerning Fluttershy. I don't want to spoil it for myself by excessively over analyzing the things Fluttershy did or did not say/imply, but I am suspecting a certain plot twist.