The little moments before and after Fluttershy was made up to be a clone of Rainbow Dash during "Magic Duel". With their futures at stake, Fluttershy knows that she herself has to try hard as well to pull off their trick in order for it to work. The little boosts that come in the form of Rainbow's love and confidence in her are usually part of what she needs.
Warning, pure fluff.
Co-written with Flutterdash7, rated for suggestive dialogue.

Twilight Sparkle summons Fluttershy and Pinkie over when she has a new spell that should let her see into different realities. She wants to see if there was really an endless number of possible realities. Pinkie ends up having Twilight royally mess up the spell; it gets overcharged and switches their Fluttershy for a different reality's Fluttershy.

Both Fluttershys have to adjust to their new lives, all while Twilight tries to find a way to switch them back.

Co-written by Poison Cure
Edited by Lathier

Discord is in love with Fluttershy, but even though he is "reformed" old habits die hard. What will happen when he enlists Rarity's help in capturing the shy Pegasus's heart?

Applejack loves Rarity but hasn't had the courage to tell her until something, or someone, beats her to it. Desperate, Applejack takes a journey to another world. With only days to get Rarity back will AJ make it in time? Being human was never easy but being in love is even harder.

Rarity loves Applejack, she really does. She loves her as much as she is able. But always in the dark attic of her heart, there is a bit of Rainbow left. Rainbow, dead by surprise attack, lost in a plot to kill the elements. Rainbow who she loved. Applejack does her best, but still the emptiness lingers.

(A Part of the Songverse, a continuity of fics I have centered around Rarity and Dash. This is non-canonical, but related. The events described and remembered come mostly from Where the Sun is Silent and it's sequel, Catch For Us the Little Foxes, but I think it can be enjoyed by itself. Yay Rarijack)

Rainbow Dash borrows Commander Hurricane's biography from Twilight, and ends up reading about various aspects of her life. She discovers that the historical once-ruler of the Pegasi also had a VERY interesting relationship with her subordinate, Private Pansy. Seeking the company of Fluttershy, who had played Private Pansy, the two of them go to reading through the rest of what Commander Hurricane shared with her subordinate.

Rated for sexual content references. Hurricane/Pansy shipping, as well as hints of FlutterDash.

Changed the title, just in case, really. ;)

As a filly, Rainbow Dash achieved two wonderful accomplishments. Earning her cutie mark and inadvertently causing a Sonic Rainboom. However, these achievements mean nothing to her when she comes to realize that Fluttershy is missing. Without her to share these gifts with, they feel meaningless to her. In all, she misses her best friend and is worried, wondering what had happened to her.

During the events of "Putting Your Hoof Down", what could've happened if Rainbow Dash confronted New Fluttershy?

~FlutterDash hints~

Song: Black Hole by Lindsay Lohan

Rainbow Dash wants to write a love letter to Fluttershy, but has no idea what certain sexual terms mean. When she asks Applejack and Pinkie Pie what they mean, they decide to mess with her by telling her that the words are innocent. Hilarity ensues. But the two Earth ponies know exactly what they're doing...

Rainbow Dash befriends and then soon dates a Pegasus named Blazing Comet. She is much like her, being fast, daring, adventurous, and can keep up with Rainbow Dash. On paper, the two ponies seem like a perfect match, considering how alike they are. Fluttershy, with her dreams shattered, now has come to believe she will never be good enough for Rainbow Dash. But as time goes on, who is to say that the rainbow-maned daredevil won't realize that the perfect pony for her was right in front of her all along?