About the kids -

Maelstro (The gray and black draconequus)

Maelstro is the first hatched of Discord and his husband Wulfy. Even before he hatched, he showed a tendency towards music and rhythm. His egg would move and get warmer if music was played to it, and he even hatched during Wulfy's birthday party when everyone was singing 'Happy Birthday.'

Maelstro inherited most of Discord's powers. Of course, Discord was super proud upon finding this out. However, instead of wanting to spread chaos and destruction, Maelstro uses his magic to create music. He is very big into electronica and has a whole dimension just to store his many instruments that he can pull out at any time.

The other siblings look up to him and see him as their Cool Older Brother Who Probably Knows Everything. He's a renowned musician across Equestria and does tours frequently.

The time period he hatched in is while the show is still going, maybe around the time Twilight becomes princess. So basically, another worry for her. Now she has to worry about new princess duties AND has to worry about a potentially dangerous Draconequus child. Thankfully, Maelstro is very chill and is willing to help her out if she ever needs it.

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Hurmey (The canine mix)

Hurmey was the second hatched of Discord and Wulfy's brood. His egg was really nothing special- it resembled a pidgeon egg actually. When he hatched, it became clear very fast that he had no magic. Maelstro was a teenager at the time when Hurmey hatched- and was PSYCHED to be a big brother. He made sure Hurmey was always included in everything. Discord and Wulfy were more protective of Hurmey than they were Maelstro- most beings in this world had magic, so a baby with no magic could be in danger. Discord basically took Hurmey everywhere with him, not taking an eye off him for a second. The only other pony he trusted with his baby boy was Fluttershy, who already had experience midwifing for Wulfy and babysitting Maelstro. She was a VERY close family friend, and still is. She's Discord's lesbian bff.

When Fluttershy would babysit him, she would often take him around town and introduce him to the Earth Ponies. She wanted to prove to him that beings without magic were just as capable of greatness as beings with magic, they just had to do it in a different way. Hurmey liked to help out at Applejack's farm (He was young at the time so he was only given little things to do.) However, one time he wanted to get an apple down from a tree like he saw Auntie Applejack do. So he tried to headbutt it and cracked one of his horns in half. He was immediately attended to but his horn would stay cracked forever.

As an adult, he is a professor at Twilight's school. He specifically teaches 'Appreciation Of Magic', but the magic he teaches about? Not the kind unicorns do, instead he talked about all the things in the world that aren't considered magical...but feel magical. Like friendship, family, love, sandwiches. All those things. He was always confident, but after attending Twilight's school and then later teaching there, he truly felt like he belonged somewhere.

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Valkyrie (The pony looking one)

Valk was the third hatched, and the last hatched of the original brood. They hatched after the timeskip in the last episode, when everyone's older. Honestly their parents were worried they would never hatch. The egg still responded to attention and was clearly still alive but it seemed like it wouldn't hatch anytime soon. Wulfy and Discord wanted to take a vacation so they left Fluttershy in charge of the egg, which she was VERY excited to do. When Discord and Wulfy got back, and stopped by Fluttershy's cottage to pick their egg back up, they noticed that....the egg had hatched and Fluttershy was fawning over it. She really went off about how magical and beautiful the hatching was and how cute this little guy was.

Valk grew up hearing about Discord's many adventures. Discord, being Discord of course, tended to embellish them a bit to make himself look cooler. He wanted to really impress his child with these stories. Valk was also a mischief maker around Ponyville as well, often getting into trouble. As they grew up, they took Discord's stories to heart, and noticed that the more bad things they did, the more attention they got. During a conversation with their best friend, Shine Sprite (Owned by @/Shenanistorm) they realized that the easiest way to get everyone to love and respect them would be to overthrow the princesses, like their dad failed to do. The two end up going through an evil arc, which ended up in a confrontation at the castle and being talked down by Valk's brothers.

To make up for all the destruction they caused, Valk was told to do years of community service to the ponies of Ponyville. A lot of them were not quick to trust them again, but they were truly sorry and wanted to show it. They ended up learning that the best way to love and respect was to make it mutual and show everypony love and respect back, and helping them out wouldn't hurt too.

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Eris (The one that looks more like Discord)

Eris was an odd egg. She wasn't created in the usual way eggs are created. Instead, on their anniversary, Discord and Wulfy had an entire day just with each other. It ended in a night of heart-to-heart discussions about their future and them both deciding they truly wanted to be together for the rest of forever. They slept curled up with each other and the next morning, they awoke to find an egg there too. They immediately reported this to the princesses, who had asked that they please not have anymore kids for at least a thousand years, and explained that it just...appeared. Twilight was super interested in this- it was the first time this kind of thing had ever happened. She wanted to know all about it and made it her personal project to watch the egg as it grew up and eventually hatched. Cadence, however, knew about this. She explained that sometimes, when magical creatures love each other with all their hearts, and they truly want it, their bond and love can merge into a new living being. She's only seen it happen a few times, but it made sense this would happen with the two Draconequus.

Twilight took the place of Fluttershy with this egg, often eggsitting it and watching over it in the castle. None of them knew the properties of this egg. Usually Draconequus eggs are indestructible, but they truly had no idea about this one and didn't want to risk it. The egg was mostly raised in the castle, with Wulfy living there to watch over the egg as well, and Discord often spending time there as well.

Eris ended up hatching when with Twilight, who ended up naming her too. She thought it was fitting, and even though Discord wanted to name her, him and Wulfy had to admit it *did* fit. That's when Twilight asked if when she was older, if Eris could become her apprentice, as Celestia did with her so long ago. Discord and Wulfy agreed, seeing that baby Eris already loved her Auntie Twilight.

As Eris grew older, she spent a lot of time learning from Twilight Sparkle and the teachers at the Friendship School, and making her own group of friends. She knows that when Twilight apprenticed for Celestia, she ended up becoming a princess. Eris hopes this will happen to her as well. She truly wants to be the first non-pony princess of Equestria and will do anything to prove it.