Sweetie Belle wants to use magic. So, who else but the wielder of the Element of Magic, Twilight Sparkle? Thing is, nothing is ever as it seems in Ponyville, and turns out Sweetie has a much larger destiny than anypony thought the little filly could have.

Found the picture on http://www.takayaiwamoto.com/draw_heart/draw_heart.html.

Notes: Though Twi and Rarity will be Main Characters throughout the story, I'm pretty sure I'll incorporate the rest of the Mane Six at some point. Also, maybe(?) I will break the show's canon if it interferes with the plot. Just a heads up. :)