I wanted an excuse to write Twilight in Celestia's position. In the beginning I'd consider it to be a position held by Twi's children but I kinda felt like that was stupid. How about a whole ass new OC? I originally also gave Twi's student a dragon but after the Dragon Emissary [Spike] discovered that dragons were raised communally that practice was abandoned. It seems ponies unknowingly were stealing dragon hatchlings.

Also do you like Twilight's design? I'm really happy with the mix of blues and purple. It makes her look more sleek. In my headcanon, Twi was always tall. She's now the tallest but before her and Fluttershy were the same height with Rarity being the second tallest.

All that out of the way, here is Queen Twilight Sparkle and her personal student Sunrise Shine

Sunrise Shine
Ilanga [by her mom], Little [by her sister and father], Sunrise
Family: "Mama Fu-fu" [Melody Festival], "Papa" Ginseng, Mkango Crest [Sister]
Voice: Sounds like Numbuh Five from Codename: KND

Sunrise was born and raised on the Eastern coast where her mother taught magic and her father was a chef. From her birth, she was a talented unicorn and gifted student. She devoured books and consistently followed her mother to school to listen in on her lessons. Magic totally enthralled Sunrise and she knew she wanted to become a Royal Mage and study at Twilight's School of Friendship.
With the help of her parents, Sunrise applied to demonstrate her skills when Queen Twilight was visiting the coastal school. Sunrise almost missed her opportunity as she studied all night and slept through her alarm. Luckily she burst her way through the door at the last second and via an incredibly strong teleportation spell which caught Twilight's eye. She along with two other students were invited to attend Twilight's School but only Sunrise ended up accepting as one of the others was also accepted at Celestia's School for Gifted Unicorns and the other got cold-feet.

Twilight was a bit surprised to only be showing one student around the campus but she found herself deeply relating to the little filly's excitement. She took notes, asked questions and even did a little dance when she was shown the school's library. While Sunrise was certainly bouncier than she had been exploring the Castle Halls in Canterlot, the sentiment was the same and Twilight was impressed. It was at that moment that she decided she would make Sunrise her next personal student since Starlight Glimmer.

Sunrise is an impish and mischievous little mare who LOVES to talk about anything and everything magic. She likes to occasionally cause a bit of trouble with her magic. She's turned classmates into frogs, dyed her professor Starlight Glimmer's mane grey, engulfed the school in large singing flowers and just generally cause mayhem with new spells! Her classmates have mixed reactions to her, some liking her as she's a leader and a lot of fun, others [like Twi's own son] finding her to be a nuisance.

Twilight often has to reign in Sunrise's antics but can see a lot of good energy in her protégé! Celestia also gets a kick out of seeing Twilight deal with her student!