WOW it’s been a while since I drew something for freyaverse, whoopsie!
I’ve been digging through my gallery and found this and ow, my eyes, but I also remembered the idea I had for the third gal (the grey one) and decided to redesign her entirely

So, meet Achromatica, or Achro for short. ( I’m still looking for other words to use as a name, but "achromatic" honestly works best for her situation, so I’ll keep it as a placeholder for now)
Daughter of Rainbow Dash and Quibble Pants, many were confused, when she was born, because her lack of color was a bit concerning. Ponies were speculating that the foal was terribly sick and wouldn’t survive, but with support from her husband, Fluttershy and Discord, Rainbow explained to her fans, that Achro is perfectly fine. Her dull colors were the result of one fateful visit to Fluttershy’s house, where Discord accidentally turned Rainbow Dash to disloyal Dash for a few seconds while she was pregnant with Achro. Although Discord assured her that the foal is completely safe, it would seem that her appearance was altered a bit.

I don’t have the story fleshed out as much as I’d like, but here are some bullet points:

• Discord feels just awful about this whole thing, but Rainbow and Quibble don’t hold anything against him.
• Achro is very self conscious about her colors, especially in school, because they give off an uneasiness about her.
• She masks the hatred for her colors with constant training and flying, but sometimes that doesn’t help either, because she’ll see "ugly brownish" trails behind her instead of her mother’s beautiful rainbows.
• She is quite stubborn and has a bit of an ego, but she doesn’t praise herself aloud like her mom.
• Is a total daddy’s girl, even though she loves her parents equally.