@Mattatatta  
Well damnit, man, it’s been years, at least tell us what that fanfic was!

I’m trying to think of words to describe how I feel about this. I do like it, but I can’t quite explain what I like in particular about it, it might be because I’m not certain if this symbolic or something.
 
It could be a symbol of Dash crumbling and turning into dust in Fluttershy’s mind, representing the memory of her fading away as time passes long after Dash left for the afterlife…
 
Or it may be something more literal, such as a horrible injury or affliction that Rainbow Dash is suffering from, and even though having Fluttershy there helps, it also reminds her that there is nothing anypony can do for her. That fact alone tears Fluttershy up more visibly than it does on Rainbow Dash.
 
It’s based on a fanfic, and I want to read it to learn which is correct, but I have far too many stories to catch up on already, and I’m in the process of writing my own.