kind of goes with the last one i posted lol. more about Discord.
after Cosmos was banished to the moon (or was it the stars?? idk her thing was kinda weird lol), Celestia punished Discord by forcing him to bear the sky on his back for five thousand years.
Cosmos' magic, however, remained long after her banishment. Grogar, a young tyrant wannabe at the time, managed to soak up most of her magic and harness it for himself. he sought to create an army of monsters that he could use to take over all of Equestria. but with the rest of Cosmos' magic expired, he had little left to create said army. so, with Discord occupied and unable to defend himself, Grogar took advantage of him.
no one knows exactly how he did it; much of that time period has been lost to history or erased by the twin sisters. some wise historians say that he simply stole Discord's magic. others say that he went so far as to split him open and steal his organs. whatever the case, Grogar combined the magic of Discord and himself to create his monsters. the first four became known as the Four Horses of the Apocalypse: Conquest, War, Famine, and Death.
with his self proclaimed sons and daughters in tow, Grogar proceeded to wreak havoc on Equestria, ruling over its people for centuries. he paid little attention to Discord, who was so deeply frightened and traumatized by what Grogar had done to him that he dropped the sky and collapsed.
Now that Grogar's gone, Discord would rather like to forget about the whole thing. it haunts him in certain ways, but he's gone through so much that it is easily outweighed. he knows more about Grogar than he'd care to. he's had many children before Grogar's offspring, and continued to have many after.
they all remain to haunt him, though.