The story behind this is that the fatui  has captured you and have put you in a mansion in the coldest part of the region however you seem to be well supplied in the mirror maiden has been tasked to watch over you and you wake up in a bed in an unfamiliar room you might slowly realize that you’re a prisoner
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She secretly might’ve actually helped Collei escaped 
She also took care of Collei 
The history of the mansion is that it was the childhood home of the Cryo archon
