Twilight Sparkle

Magical ability
Twilight is smart, bookish, and skilled in every type of magic there is. She is also the poster-filly for the myth that complex unicorn spells are unstable and that the slightest bump or a poorly timed sneeze can end up transferring body parts, swapping genders, or teleporting ponies to lands unknown. She's sometimes shown as very dependent on her books to work her spells, being unable to do more than levitate objects or teleport short distances without a written spell formula in front of her.

In the show, her power is notable enough to have drawn Princess Celestia's attention, and both there and in fan works she is most often proud of her status as the Princess's personal protegee. Even before 'Lesson Zero', fans were sure that Twilight still shared a deep respect (at minimum) for the princess.

One semi-popular trope is to have Twilight's research or spellcasting somehow go wrong or out of control to set the events of a story in motion. Another is to show that her power and/or ability will enable her to 'evolve' into an alicorn like the Princesses.

Science
Another fan depiction is for her to also be the main scientist (or even mad scientist) type, typically based on her reaction to Pinkie Pie in 'Feeling Pinkie Keen', where she subjects Pinkie to various measurements, including hooking her to some sort of analysis machine in her basement. Continuing this theme involves either magic-assisted technology (such as reprogramming magic-based computers), or even eschewing magic altogether in rare cases.

Non-romantic relationships
Aside from alternate universe or other extreme variations, generally in awe of Princess Celestia, as a mentor and teacher. Some stories will even try to work the traditional letter to the Princess in if Twilight is the main character. And even before the events of 'Lesson Zero', she is normally shown as concerned with he rstanding with her.

Early fanworks (prior to 'Cutie Mark Chronicles') would hypothesize about Twilight's ancestry. One theory was that she was actually Princess Celestia's daughter, whether by birth, adoption, or both. Generally, most fans after that episode understand that Twilight had a normal family upbringing.

During the aforementioned episode, she is shown hatching Spike from a dragon egg. Many thus have Spike feel as if he is an actual family member of Twilight, with her responding in kind. This usually takes the form of either mother-son or elder sister-younger brother.

Shipping
She is most often shipped with ponies of similar or greater magical power, such as Trixie or one of the Princesses. Many of these cases feature her as being less worldly than her would-be partner, even Luna. Of the other 'mane 6', shippers seem to have no outright favourite. Rarity appears as a fellow unicorn and adorer of Canterlot culture; Pinkie Pie is a mystery with abilities beyond pony knowledge; Fluttershy and Applejack are down-to-earth ponies; and Rainbow Dash is shipped with everypony. She is rarely shipped with Spike, given how close they normally are (as well as Spike's own canon feelings towards Rarity).

Twilight in fan art
In non-narrative fan art, Twilight is commonly associated with books and reading. A crudely drawn piece of art by seniorpony titled "the pen is lonelier than the" has become quite popular and garners occasional derivative works that copy both its drawing style and its structure, with a character exclaiming "God I love X" in the second panel. "Books, God I love books" has also become a bit of a catchphrase associated with Twilight.

On February 12, 2012, Tara Strong, Twilight's voice actress, approvingly replied to a tweeted picture that inserted quotes from previous tweets by Strong into the "God I love books/I'm so alone" template.

Confronting Twilight Sparkle with the book and film series Twilight by Stephenie Meyer, or crossing the two franchises in some other way, is also a fairly common subject in fan art.

Gallery

 * Twilight Sparkle image gallery

Fan art examples
