So Imma say it now that is not Fluttershy’s foal.
 
Discord is a physical embodiment of chaos. I believe Grogar made him and set him free to cause that chaos and disharmony. (I know everyone theorizes that star swirl made him but eh.boring.)
 
Anyway, Just as he was made of dark magic and the skeletal remains of random animals he could do the same to bring forth a heir. Minus the use of skeletal remains. It’s more like sugar, spice and a sprinkle of chaos magic and poof he can make himself a little spawn the bad thing is he can’t control how they look. So he can want a son all he wants but he might not get it.
 
Draconequus babies are lots of work, just as Alicorn babies. Flight and the magic outbursts it takes a lot of time and energy to care for them.
 
This is Discord’s first daughter Gaia. She’s more pony looking than her younger sisters.  
Aside from the green horns, leg of a turtle and a cloven hoof she’s good.  
Fluttershy steps in just watching over them when discord can’t. She doesn’t mind he’s her friend and he obviously needs help raising the little spawns.
 
This was a old sketch I finally got around to finishing.  
Yes his legs are flipped and are on the wrong sides but I wasn’t thinking and forgot to change it as I lined it. ;-;