Princess Celestia's faithful student, who is secretly plotting her downfall and is willing to go to any lengths necessary to ensure it. The tragic loss of her parents left her being stuck in her care, giving her considerable insight into their ruler's facade.
Not So Different: Can be just as manipulative and cruel as her teacher. Showcased in "Dragonshy", where she tries to force Fluttershy to kill a dragon in order to prove her loyalty, even going so far as to mind control the beast.
A perky, playful pink pony who finds joy in just about everything. Everything including carnage, death and destruction. Though her parents rejected her and her gifts, she's learned to always look on the bright side of life and your knife~!
Start of Darkness: The horrible treatment she recieved at the hooves of her parents nearly drove her to suicide; however, witnessing the Sonic Rainboom helped her see a bright side to everything... including murder.
An elegant seamstress who considers herself a truly rare jewel, and believes her dresses reflect that perfectly. Beautiful, manipulative and vain, she'll seize any opportunity to gain the respect, attention and love she knows she deserves!
Start of Darkness: When she didn't get to perform in the school play, she decided to make the costumes so dazzling that they'd overshadow the foals wearing them. Discovering her destiny led to her learning black magic that she tested out by turning everyone who attended the play's premire into her fawning servants.
Vain Sorceress: Very proud of her appearance, and uses magic to make herself even more desirable.
A seemingly sweet Shrinking Violet easily dismissed as too timid to do much of anything on her own. Underneath that innocent exterior, however, lurks some very dark thoughts — thoughts which have been building under the pressure of years of unpopularity and isolation. Only her tight bonds with her animal friends have kept her sense of empathy strong — for them, anyway.
Pacifist: While she's fine with nature taking its course, she isn't comfortable with ending a life herself... which fuels the main conflict of "Dragonshy", as Twilight wants her to help kill a dragon to prove her loyalty.
Pure Is Not Good: She loves her animal friends... but has no problems with them eating each other. It's all nature at work.
Sadistic Choice: Break her moral code and help murder a dragon, or stick to her ways and be labeled a traitor for it?
Shrinking Violet: Which made her unpopular at school, only feeding into her shyness.
Start of Darkness: After being treated like crap because of her shyness and difficulty flying, she met Rainbow Dash, who defended her... only to knock her right out of the sky during the resulting race. Still, this led to her discovering her talent with animals... and meant she was outside Cloudsdale when it got destroyed by the Sonic Rainboom, making her one of the only survivors. She doesn't mourn the loss.
A cocksure pegasus who commands attention, Dash is the only pony who's ever successfully pulled off a Sonic Rainboom, a feat that's left her with a swelled head and an ego to match.
Where I Was Born and Razed: The destruction of Cloudsdale by a Sonic Rainboom. Her thoughts at the beginning of Sonic Rainboom imply that it wasn't on purpose, though.
After losing her parents to a tragic accident, Applejack was left in charge of the family business. Hard work and huge sacrifices must be made to survive in that cutthroat world — she learned that much very quickly, and has dedicated herself to ensuring it prospers, no matter what.
The eternal ruler of Equestria, a beautiful alicorn loved and feared by all. Though hailed as a benevolent and wise ruler, she hides a sadistic side beneath her constant smile. Her sister Luna saw through this facade, leading to her failed rebellion. Now her faithful student is following the same path... but just how much does she know...?
A God Am I: Best demonstrated toward the end of "A Dog and Pony Show".
Celestia: (about Twilight) I am not afraid of you, your friends or anypony. You are still breathing because I allow you to. Everypony in all of Equestria is alive for that very same reason as well. Your entire life, I have guided you to the right path, my dear. Your destiny as the element of Magic has been known to me all along. You have what I want. Taking it from you however is quite a lovely challenge. You are mine, Twilight Sparkle. I made you. It's only natural for me to destroy you as well.
Anti-Magic: A power she demonstrates when helping the Diamond Dogs kidnap Rarity.
An envoy of Princess Celestia who was sent to check on Rarity's progress after the unicorn was charged with creating their ruler's dress for the Grand Galloping Gala.
No Sympathy: Dismisses Rarity's work as 'mere glitter'; when Rarity reveals she used all her diamonds on that dress, smirks cruelly while commenting she'll have to find more.
Formerly Celestia's little sister Princess Luna, she came to realize the depths of Celestia's depravity and tried in vain to warn everypony. For her troubles, she was painted as a jealous, powerhungry brat and was ignored and scorned. Desperate, she turned to the dark arts and became Nightmare Moon in order to overthrow her, only to get sealed away in the moon for a thousand years. This didn't quell her desire for revolution at all, and upon her return, she immediately tried again.
Black Magic: When nopony was willing to support her, she turned to the dark arts to find the strength she needed to stand against her sister.