Horses: the third

Well, I couldn't resist. I was sitting my younger cousin and I was forced to watch MLP. So I watched it w/ her,,,, then Vulcan and Eris were made...

ERIS
Daughter of Discord and Princess Celestia

The Draconequus-Alicorn hybrid who is heir to the sun throne named Eris is.... quite a handful. She's 14 and is already HUGE, her weird magic puberty isn't quite over yet- she's far too emotional, has crazy magic spurts (once accidentally filling her entire room with pigs), isn't quite used to her new power, and her body is very unproportional- her body is large but not LONG like it's meant to be. Probably hindered by her pony blood.

She takes a playful personality moreso from her mother, but she has the same love for absolutely ruining everything like her father. Much to everyones distaste. She's loud, annoying, obnoxious, and invasive. Though she is always somehow forgiven thanks to her puppy eyes and the small sweet part of her SOME people can appreciate.
Eris could very well be responsible for april fools day, she loves to scare everyone to death in canterlot by doing silly things like turning the pavement into candy or making it rain chocolate milk (daddy would be proud). The only reason she gets away with it is because it makes the ever so serious Celestia burst into tears of laughter. And boy, does Eris love making her mom laugh.

VULCAN
Son of Princess Luna and the top of the Royal Night Guard

Vulcan, who is very soft spoken and somewhat harsh, is the heir to the moon's throne. He is far different in personality than Eris, mostly taking from his mother, but he does in fact have some emotion... He just doesn't show it. Vulcan's father, who he looks up to more than anyone else, died in war. He was a bat pony and the best of Luna's army, and perhaps the best in Luna's heart. Vulcan loved hearing about his father when he was a foal, and models himself after that beautiful image he has of his father. He was somewhat sheltered as a child, it was unheard of for royalty to have a child with anyone of a lower class... So Vulcan was only something kept within the kingdom. However, when Eris was born and accepted by all of Equestria, Vulcan finally took his first steps into the world at the age of 10.

Vulcan could be described as impulsive, with his entire life being set one way- he could not stand to have it changed. He has a one track mind that really cannot be changed. Luna worries for how her son who makes so many mistakes with his astronomy studies (because NO, it is TOTALLY right that this constellation is in this star cluster- I know what I'm talking about!) could rule easily. He goes into panic mode at the smallest thing- he once tore apart his study because he couldn't find his pen, Luna stopped him once she took it from behind his ear. 

However, despite all of his flaws, Vulcan could call himself a pretty damn good prince, one who's organized and definitely NOT a worry wart