During your exploration in Backwater Pass, you might stumble upon little girl NPC named Mysterious Girl. Later revealed as Cyrille, alone surrounded by mysterious box. Spoiler ahead, interracting with her will start quest Vessel of Mediocrity (Part 1).
To Summarize the quest, you will help her to “escape” the box surrounding her. After that you still failed to gain any useful information, you bring Sampo to the area for help but she dissapear. End of first part
For second part of this quest, you will find Cyrille as “Mysterious Woman” in southwestern part of Silvermane Guard Restricted Zone after real time 24 hours. More or less this quest will be the same, you help her escaping box puzzle, she dissapear, and you failed to gain any infomation about her.
For third part, after getting message from Dunn you can find her in Everwinter Hill where she will manifest as Guardian Shadow. Talk to her, help her escape from box, and she will tell you eveything about her. After “sending her off”, back to Belobog and talk to designated NPC where you get a full story about Cyrille.
An Old Diary
Obtainable after completing Vessel of Mediocrity (Part 1)
Quest Location: Backwater Pass
An Old Letter
Obtainable after completing Vessel of Mediocrity (Part 2), then reporting to Dunn.
Cyrille “The Fool”
Obtainable after completing Vessel of Mediocrity (Part 3)
Based on all notes above, it’s implied that Stefan and his cronies are responsible for Cyrilla “mysterious dissapearance”. He then push Cyrille to become Supreme Guardian, later become puppet for him. Make his position stronger in fort Qlipoth, until the day coup happen.