Here is a final image of an non-player character from the online Tails of Equestria adventure for which I acted as the game master recently. By now our group of adventurers has moved on to Manehatten and the role of the game master is now held by SandySRose  
Much as I enjoy the role of the game master I must say I relish being a player again for the time being and exploring the world through the eyes of my oc Leafhelm.
 
Anyway as for Maid Mareian up there, to get the elephant out of the room, yes she is a recoller, or even a mere color swap between mane~~/tail~~ and coat color of Fluttershy. This was done very deliberately as a bit of a clue to the players. Not only would this pony (who they hardly met during the game because of the decisions they made) act very much like Fluttershy but also…
 
 
SPOILER ALERT
 
…she is not actually a pony. Maid Mareian here is a changeling. There were further subtle clues in the game that might have given the players the right idea. Instead of butterflys her “cutie mark” is a cocoon. At several points in the game where important things were said in the game I mentioned the presence of birds (one of whom would have been her) and she comes with the feather in her mane. Her hoofwriting is also deliberately given a somewhat less refined look compared to that of other ponies in the game. Last but not least some interactions with other NPCs in the game might have lead the players to the right conclusions.  
In any case it is of no harm that the group in game did not solve the mystery of Maid Mareian, for she is not some vicious spy on behalf of hostile changelings but rather a last remaining changeling of a hive that left the Griffish Isles long ago (another ingame clue for the previous existence of changelings there was that some of the mine tunels underneath Trottingham were not dug by pony but had been there before and had the rounded appearance we have seen in changeling hives in the series).  
Maid mareian avoids most of the ponies most of the time for fear of being uncovered, but at the same time she often offers comfort to those in distress (Scarlet Temper in particular) getting some affection to feed on from it. In fact Alan a’ Foal (the minstrel who often showed a melancholic trait) while courting Maid Mareian discovered her secret, but in spite of this didn’t wane in his passion for her and kept her secret. And yes, Maid Marian in a changed appearance is the “manifestation” of Robbing Hooves who the players met in the forest, while the actions of Robbing Hooves are actually the work of a number of different ponies over the years.
 
Back in 2017 I had played a different version of this adventure with different solutions, but Maid Mareian as a changeling was already part of the plot and I had made this picture of her back then already.  
I think one inspiration for the idea was the fanfiction Yes, it matters by RHJunior, which (set in the aftermath of the Canterlot wedding) gave a very interesting idea of Fluttershy actually being a kind changeling. Of course the official canon has by now made clear that this is not the case, but I still think this beautifully written (and beautifully read by DRWolf001) fanfiction is very intriguing.
 
SPOILER END
 
There is also an alternative version of the above image without reduced opacity.