Trixie

Trixie, often called The Great and Powerful Trixie after the stage moniker she gives herself in the episode Boast Busters is a unicorn who quickly became a popular antagonist and even main character in fan works despite only appearing in one episode.

Trixie's life post-Boast Busters
Her characterization by fans differs wildly depending on the work she appears in. Her fate after running herself out of Ponyville is one of the biggest speculations.

More often than not, she seems to end up lost in the Everfree Forest for a time, bruised, hungry, and either burning with rage or crying her eyes out in despair. If she remains in the forest, she'll either begin to starve or find decent forage while she plots her revenge upon Twilight Sparkle. Said revenge plot may either become a truly epic endeavor involving the release of forbidden magics, demons, Nightmare Moon, or simply an attempt to trip Twilight up and mock her.

If Trixie avoids the Everfree, she'll end up in Canterlot trying to gain an audience with Celestia for any number of reasons, good and bad, or in another town or city in Equestria where she will attempt to rebuild her image with the shadow of Ponyville hanging over her.

Skill in spell-casting
Trixie's actual spell-casting ability is open to interpretation. The show makes it clear that she has much less ability than Twilight Sparkle, but also suggests that Trixie is genuinely skilled in comparison with most other unicorns, who only "have a little magic that matches their special talents". In fandom Trixie is sometimes depicted as having nearly as much magical power as Twilight. The pair make for great rivals in cross-overs, as they are perceived as two sides of the same coin. Trixie is proud and impetuous while Twilight is modest and logical.

Relationships
Events usually transpire to bring Trixie and Twilight together, and it is not uncommon for them to end up romantically involved. If not, Twilight will teach Trixie some friendship values and the two will part ways on a pleasant note. Either way, Trixie usually ends up "redeemed" with a fresh attitude and a world of success on the stage.

Early in the fandom, an illustration of Trixie with an enshrined photo of Twilight was drawn. It was created in a likeness to Helga Pataki from the Hey Arnold! series, who is secretly in love with Arnold. Starting in February 2012, Trixie is occasionally depicted with a plush Twilight doll for a companion, who she pretends to be real.

Shortly after Boast Busters aired, it was suggested that Trixie's most likely pairing, if not Twilight Sparkle, would be with herself. Artwork of her having dinner dates with a mirror, or cloned Trixies, obtained popularity.

Trixie and pinecones
In fan art, Trixie is occasionally associated with pinecones, usually eating one. This trend was started in July 2011 by a fan named BronyMike, who details the origin of the meme in a tumblr of his, beginning with this post.

Gallery

 * Trixie image gallery