Ok... I've tried to explain to someone what I mean when I say that it's best to make your own world when go to make your own character. This person, who had gotten banned from DA for some reason I don't know, was using MLP:FIS as their base world, hence the reference.
As a side, I've only seen a few episodes, thankfully, the one that was needed to help communicate this entry a little better was one of the... what?... 4-5 I've seen.
Good fantasy bends certain fundamentals of reality and physics and delves into the realms of supernaturalism. MLP does that with it's own elements of magic (which I find confusing as to why Twilight had to explain Pinky's twitch-predictions with science when she can use magic [logical paradox=headache]) and personified, candy-colored ponies/pegasuses/unicorns/pegacorns. Other than that, natural laws of physics and the urethral laws of life itself still govern the MLP world/universe as they do here.
I'm not saying that your fandom character is bad, I'm saying that the characters that YOU created are in SOMEONE ELSES world, thereby being governed by laws that you didn't create. This stunts their overall growth.
Darkverse (my Pokemon fanfic) never went anywhere because of this simple truth. Cerou, being bound by the general laws of the Pokemon universe, couldn't grow further than that of the Rival from D/P/Plat. (who he was based off of and, essentially, fleshed out further than the game's writers) was capable of if he went the right path.
THIS is why fanfics aren't taken seriously, even if the fan-base is large enough, ESPECIALLY when you're putting characters of your own creation into someone else's world. Cupcake (never read but heard about it) worked because it seriously twisted the existing characters in MLP to create demented horror story. It mostly worked based on the shock factor.
To summarize and simplify, for the sake of the fantasy genre and all who have come to appreciate it like Rocky does boxing, MAKE YOUR OWN WORLD/UNIVERSE! Your ideas, your characters, and your story are too important and valuable to confine to someone else's interpretation of the world around them. I'm not saying that you shouldn't make fan-fiction, not at all. If you're going to take the time and effort to make your own character, ESPECIALLY if the character is based off YOU and who YOU would like to BECOME, go the extra mile and me your own universe to put the character in. Even if it's a modified version of true reality, and a crappy one at that, time and observation will make it better and you can say with full confidence that it's YOUR work.