Castella got her name because Twilight was craving castella cakes constantly when she was pregnant with her.
Considering how busy her parents are Castella is always with her caretaker. She’s nice tho her name’s Miko and she’s from Japone.
Castella’s nickname is Ella (by very close friends) and Cas by mutuals.
Cas can feel someone’s emotional aura, so she’s always vibin.
Eventho shes a deformed Alicorn her magic abilities are still considered above average then normal unicorns. She just struggles with controlling it.
The necklace she wears has some of Twilight’s magic store up. Most if not all young royals do have their parents magic stored up in a charm, this is to make sure they’re protected while their own magic is still developing. It can also assist the young royals in combat training or magic practice. Basically a training wheel. When they’re ready to take the throne, they wont need these charms anymore.
Also you can find a grownup version of her on my gallery somewhere.