Location: Ponyville (outskirts), Equestria.
A childish, sarcastic pony who is a fast flier and would do anything for a friend in need. This pony has a black coat, a red mane, scarlet red eyes, and a red and black swirl Cutie Mark with sparkles outlining the red swirl (similar to this: [link]
And excatly like this: [link]
, if stared at long enough the sparkles may even shimmer. He has more of a feminine athletic build rather then a bulky body as would be expected with a male Pegasus pony. His voice too is unexpected, higher then any males well still being lower then a females, also sounds slightly rough.
His past, including his birth, is shrouded in mystery even to himself. He was found as a very young colt deep in a unnamed forested area, interestingly his Cutie Mark was already present, but a different color then the current. It is said when he was first found he was all grey in color, over some years his mane and coat changed to every color of the rainbow. Sometimes overnight. Until finally it settled to its current coloring.
It has been found that he has magic in him that is unique, somehow. It is rather mysterious as a whole in how strong or even in what it can do. Recently he discovered he can change his mane and coat color for a long period of time.
He has the personality that resembles the one and only Rainbow "Danger" Dash.
Not surprisingly, or maybe surprising to some, he has a major crush on her.
Because of his color changing ability, personality, and crush on Rainbow Dash he likes to make himself look like her and try to pass off as her twin. He can even copy her Cutie Mark and eye color. And with how his body is built, and voice being so close on top of that, there is no way to really deny that he is her twin, or even her for that matter if seen from any further then only a few hooves away and aren't looking closely. Rumors say he likes the attention of "being" her, or her twin, well others say it is him trying to honor her in some way, or could be both. He normally stays in his "regular" color however. And even though almost every pony knows about his ability he does not boost about it, nor does he ever change color in front of anypony. When asked about why he never shows himself using his gift in front of anypony he will say it makes him uncomfortable.
Authors note: The official "unofficial" full name of this Pegasus is Firestorm "Danger" Dash. Most likely from his closeness in personality and actions to Rainbow Dash, besides the whole twin thing.
One other thing, to avoid any confusion, he can not change his body shape, size, build, or even hair length. Unless of course through long natural means like anypony else. That being said he obviously keeps his hair long and very much like Rainbow's hair for reasons already stated.
P.S. It seems ever since the attack on Canterlot from the ones called "Changlings", the origin of Firestorm and even "what" he is has been put into question.