Well, there's no fan fiction but, there is a "story based" tumblr that this was made for. It follows a steampunk version of Doctor Whooves and Derpy, along with their friends: Captain Jack( from Doctor who), Dinky, Sparkler, Twilight, and Luna.
It appears this Twilight went for a more artificial approach with wings. Well, as long as it works. And it doesn't make her any less beautiful. Lovely work with the appearance of the metal frame of the wings. I can feel its thickness and the texture of its metal. Really well done. She has a lovely mane. The somewhat less straight-lined, curving approach fits the mood and general feeling of her appearance well. Nicely highlighted, too. Pleasant detail on her cloth and that pen. Interesting ornaments there. And that broach/collar is quite lovely. Also, the collar of her shirt says TWI—, an interesting touch indeed (and makes me wonder what's written in full there). Also, it appears Rarity made her a hat. Well, it's not bad for writing things in. Nice detail on that illustration thing on the scroll, too. And good reflection of the texture of the couch. And finally, those lovely, lovely eyes. I like the way you did her eyelashes, but the eyes themselves, with how beautifully reflective and expressive and deep they are... I could look into them forever. Ah, Twilight, I love you so... <3