This bab is the child of Rainbow Dash and Night Glider.
After the events of "The Cutie Map," Rainbow and Night Glider had kept in contact with each other, forming a sort of friendly rivalry between themselves. They often practiced together and Rainbow even encouraged her to try out for the Wonderbolts, seeing the skill and potential she had.
Glider flunked out of her first attempt, but her and Rainbow continued to train with each other to hone her skills.
During this time, Rainbow had her encounter with Wind Rider, exposing him for framing her for what he did, just because he didn't want her to beat his old record.
Both Rainbow and Glider had looked up to him, and it was a real blow to both of them to find out that he was the way he was.
But, even though Rainbow didn't have anyone new to look up to, Night Glider found herself looking up to her friend.
With more encouragement, Glider passed her test and eventually does become a Wonderbolt, but it was delayed for a while because of an "Unexpected pregnancy."
Rainbow and Glider had grown more close to each other as time went on, and eventually they had relations with each other that ended up with Glider Pregnant.
She had their child, and Rainbow picked out their name for them, Iridescent.
Right now, tbh this ship is really growing on me and might be a thing. At first I had imagined them parting ways peacefully like Rainbow did with Pinkie but ughds afjksdl;ajfkl; I SHIP TOO MUCH
Like, imagine Rainbow affectionately calling Night Glider "Sugar" asjfkls;ajfkl;a