First part of my MLP headcanon drawings! Just my own little take on each character c: Some aren’t dramatically different while others are! These are just coloured cketches so excuse the roughness  

 
Celestia:  
Tainted from the use of the Elements of Harmony and the banishment of her sister, the rift between the two has never fully healed. The last 100 years have been rough and stressful upon the Princess. She’s never forgiven herself for banishing Luna or really recovered from shouldering both duties.
 
Celestia is constantly exhausted due to but thankful to have her sister back to help, even if things are very strained between them. She hasnt had a proper nights sleep in years, she manages an hour or two at best and generally gets by with just power naps.
 
Constantly in the public eye, she’s bombarded with public appearances she’s gotten very good at putting on a brave face and a smile.
 
She’s rather full on with Luna at times, often trying to smother her with affection and is met with coldness in return.
 

 
Luna:  
Her transformation to Nightmare Moon has affected her appearance and mind. 1000 years of isolation with nothing but dreams to comfort her have not sat well with the younger sister.
 
Adjusting to normal life again has been hard, she struggles daily with it, preferring to sleep in the day and stay awake to watch over the dreams of other ponies.
 
Awkward and withdrawn, Luna is seldom seen apart from in dreams but does make the rare public appearance for big events, but always makes an excuse to leave quickly. Luna prefers for she and Celestia to have as little to do with each other as possible, she understands why her sister did what she did, but the wounds and mental trauma are still very fresh.
 
 
Twilight:  
Going by just her first name these days, Twilight has undergone a rather dramatic transformation upon gaining her princess and alicorn status. She gradually grew taller and more elegant, her mane picking up a gentle movement and dappling with stars.
 
Twilight has matured considerably as well as calmed down, she has come to terms with her role as princess and is currently working on trying to bridge the gap between Celestia and Luna.
 
She see’s less of her ponyville friends than she did before, but for the most part they all understand. Twilight is very much enjoying running her friendship school in hopes that history never repeats its self again. She enjoys tucking herself away in the school and teaching her students what she can.
 
The role of both teacher and headmare sit very well with her, Twilight soon changed her friendship school to a boarding school and took up residence there.