A reality bomb has detonated, scrambling the biology of Equestria`s dominant species with their alternate selves, When this new world was created a lot of extra chaos magic was introduced to equestria.  
Discord and Twilight believe that he came into existence after a similar incident to control the extra chaos that their world couldn’t handle.  
The same has happened again, and now discord is stuck babysitting and teaching Eris, the new co-spirit of chaos.
 
https://derpibooru.org/958358?scope=scpe4aa52b0eae71b0fb22be10b4bbea282a1c6b9649 Mane 6  
https://derpibooru.org/959206?scope=scpe4aa52b0eae71b0fb22be10b4bbea282a1c6b9649 Celestia and Luna  
https://derpibooru.org/996418?scope=scpe4aa52b0eae71b0fb22be10b4bbea282a1c6b9649 Eris and Discord  
https://derpibooru.org/1005916?scope=scpe4aa52b0eae71b0fb22be10b4bbea282a1c6b9649 The Cutie Mark Crusaders  
https://derpibooru.org/1008443?scope=scpe4aa52b0eae71b0fb22be10b4bbea282a1c6b9649 Nightmare Moon  
https://derpibooru.org/1008709?scope=scpec8f6165c89ee4530652c92a14c7fe5d2f72d4750 Daring Do