This is derpy hooves in the new au I thought of last night
 
she is a draconequus/Cosmos’s species hybrid (Cosmos is a villain in the IDW comics)
 
here is some backstory/headcanon:
 
DERPY HOOVES; is a Pegasus with a condition that makes her eyes go out of alignment with each other and a secret: she is actually the half sister of Cosmos the personification of malice itself. Derpy’s real name is Anomaly, she is not evil like her sister and came to equestria seeking a solution to her sister’s madness. Little did she know that a draconequus was putting equestria in peril and was actually the boyfriend of Cosmos herself, his name is discord. Anomaly was shocked to discover this and went into hiding turning herself into the gray Pegasus we all know and love.
 
When cosmos arrived in equestria and started wrecking even more havoc then discord was doing, Anomaly (as Derpy Hooves) could only watch and wait as she was no where near as powerful as her sister and knew she couldn’t stand up to Cosmos even if she tried.
 
when discord and Cosmos where ultimately defeated she stayed in her Pegasus form out of fear that the xenophobic ponies of equestria would drive her out or do the same thing that they did to Cosmos and Discord. Anomaly would go around equestria pretending to be a (mostly) normal Pegasus; she would start her Pegasus form’s life as a foal in an alleyway hoping that somepony would find her, then she would “grow up” in that town or with the pony/ponies that found her, she would then fake her death at an old age and move on to the next town to begin the cycle again.
 
This went on for a few thousand years until she came to Ponyville where she started the cycle again but as she was a young adult she came across the mane six and after awhile the purple pony leader of the mane six became an alicorn, the princess of friendship no less, she started to realise that equestria was changed, the nation was no longer xenophobic: there were non ponies doing all sorts of things like being models, librarians, police officers even, even Discord himself had come to see the value of friendship so she decided to finally change back to her true form…
 
 
(I can’t really think of anything else right now so here is some things to note about her)
 
THINGS TO NOTE  
>she never used to have her Pegasus form’s cutiemark on her true form’s chest but after being in the Pegasus form for so long it kind of grafted itself onto her true form  
>Celestia herself had noticed the Pegasus a few times throughout the thousands of years that Anomaly had been a Pegasus and she had wondered if there was more to this cross-eyed Pegasus that kept popping up at different times during equestria’s history, the princess never really looked into it  
>being half draconequus half Cosmos’s species Anomaly’s body is longer then Cosmos’s body but shorter then a regular draconequus