So... You like dark, then, eh?
Could you do a lovecraftian abomination fluttershy in a pose based on this?
Basically, the idea is that somehow, Angel managed to open up an evil portal through which the imprisoned spirit of an elder god escaped, and Fluttershy just happened to be passing by.
Her personality would be a strange mix of Fluttershy's overly-polite nature and the elder gods' supremely evil dominance over the shadow realms.