Feels good to be bad.
 
Discord probably would let cosmos go on an unhindered rampage if it meant he gets left alone.  
Good thing theres a woman around to set him straigh.
 
Being a draconequus has its perks.  
As a normal pony, Fluttershy would have sorely fallen for the rewriting of time, as Cosmos medeling with her friends past lives would have left her stuck percieving the new timestream (the new cosmic truth) as the only one.
 
But you cant fight chaos with chaos - youll just end upp with more chaos.
 
But as a draconequus, her brain retained the memories of a deleted timeline. And they made themselves known as a little voice in her ear begin to wisper of foul play, quite literally, as the Chaos that ran through her veins made her little shoulder-shy’s (the avatars of once good ans bad side) manifest litterally, and argue. One for the old timeline. One for the new.
 
Fluttershy might not be used to the powers that Discord has given her, but they let her see through Cosmos trickery of time. As the contradictions made her third eye open in her left eye-socket, and she knew that someting was afoot.
 
 
Discord: Cosmos seems a little distracted right now. Maybe we should just leave her be and she’ll leave us alone.
 
Fluttershy: Discord. They were youre friends too.
 
Discord: well, with their backstories being rewritten backwards through time they technically never were, and besides, they look so much happier now that they are her.
 
Fluttershy: DISCORD!
 
Discord: Ok ok, ill think of someting.