This is a theory I heard while playing with some fella called JuicePrime and it’s pretty solid reasoning.
There are some spoilers for VT1 so if you haven’t played that and you want to then don’t read this stuff.
Let’s take a look at Olesya.
Grey hair, Grey hat, Grey beads, Grey clothes,grey feathers in her hat. You can see where I’m going with this already. If you go and check out the little area she is hobbling around in while she’s at the keep you can see some broken mirror shards on the table(known ingredients for grey magic), books chucked around all over the place like in the Wizards Tower from VT1, and for those of you who completed the Trial of the Foolhardy one of the open books on the corner of her little table contains the image of the open pages identical to the pages of the invisible book you needed to stand on to open the portal.
If you go and have a look at the sword at her hip it is very luxurious compared to everything else she is wearing - a purple velvet handle with gold trimming and pommel. Nice weapon for a grey wizard who favours melee.
Oleysa was never seen at the Red Moon Inn until the very last mission “waylaid” where she appeared in the cellar once you dropped down through the floor. She is also obscenely powerful - being able to mind-speak to Kruber during the prologue, infiltrate the rats at will to find out all kinds of information, apparently moving among them unnoticed.
She always turned up somehow with the shadow horses pulling the carriage and appeared with a boat whenever she fancied in VT1.
In short the theory is that Olesya Pimenova is, in fact, Christoph Engel in disguise and has had a much greater part to play in the whole affair than just casting an illusion over the Red Moon Inn.
What do you think?