oh mister discord what do I do with you. I feel like I've grown weirdly resentful of a lot of the male characters on MLP, especially the one off assholes who get a disproportionate amount of fanwork depicting them as misunderstood sad boys with a heart of gold, meanwhile a lot of the fanwork of the female characters on MLP turns them into one-dimensional cutouts of themselves. Honestly though, it's just not fun to write one dimensional characters..so my idea of turning Discord into a big dumb asshole in my verse as an act of rebellion was kinda dumb.

So. Discord. White Rabbit's absent, otherworldly bio-father. Not sure what I'm doing with him, but here's what I know so far:

Discord is the first and last of his kind, and he wasn't born as a "draconequus". He was originally a pony, given the gift of shaping the world into something better and more…exciting! Eventually the power drove him mad, as is usually the case in these situations. It also resulted in…interesting changes to his body, where the new creatures he created had a physical impact on him. Creations reflect their creator, right? Who says that can't work backwards?
He doesn't remember his original pony life. He had parents and friends probably, maybe there was some kind of threat that spurred him to discover and harness the power to change the world around him. Maybe a volcano, or an asteroid, or a war. But the stronger his power became, the stranger things became for him…his memories were jumbled and foggy, he woke up with new body parts he never had before, or had he? He seemed to experience time itself chaotically.
The reason for this is the source of his power: a black hole. Like Luna and Celestia's power is drawn from the moon and sun, Discord draws his magical power from the highly concentrated forces at the center of the galaxy.
Discord is definitely connected to Luna and Celestia in some way, hence why his wings look like theirs. I haven't figured out how yet but I'm sure it'll be great when I do. They're not going to be related though. There's no way I can make that work, I couldn't even make Celestia and Luna related
Discord has a LOT of children scattered throughout history. Many cases of a pony having a new/strange physical appearance are a result of Discord…"meddling" with ponies. Some of his children do take after their pony parent strongly and appear to be just ponies with strange features, but many take after their daddy Discord and have a more…monstrous appearance. Their reception by pony society has been VERY mixed, some were considered monsters or freaks while some where considered gifts from a higher power and/or powerful guardians. It honestly depended less on the child themselves and more on the social conditions/family they were born into. A child raised as a monster will likely turn into one, and a child raised as a guardian is likely to turn into one as well. Discord is immortal himself and while many of his children were blessed (or cursed, depending on who you ask) with extended lifespans, none were immortal. Ol' boy has slowed down considerably in modern times, and White Rabbit is his only currently living child. Not that he really cares.
probably 90% of the reason I don't draw discord much are his stupid horns which I can NEVER make look good