The page below contains MASSIVE SPOILERS of the main Breath series, read with precaution.
Rainbow Dash, know as RD by Skyblack, is a major character in the Breath Reboot series and a minor character in Breath (Original) and Breath: The Fall of Celestia. She snitches Skyblack to the authorities in the reboot. She's notable for being an actual character from the My Little Pony: Friendship is Magic show.
Rainbow Dash is mentioned by Skyblack in episode two. She hung herself after Pinkie died. She is not mentioned again.
"You think you're funny?" - Rainbow Dash to Skyblack in episode four.
Rainbow Dash plays a huge role in the reboot, torwards the end. Not only she mocks Skyblack all the time, but also, after figuring out he's the killer, she snitches him to the authorities, following by serving as witness in court, resulting in Skyblack being considered insane and throw into the Ponyville Sanatorium.