The Eminence in Shadow: Black Ice(Il Capitano OC x EIS)

Darkness lurks in every corner, no matter where or what spot it is. And in that darkness, shadows lurk to claim all. People fear the dark, but they should be more afraid of what's INSIDE the dark. Two brothers, with a fascination for being shadows, have their chance handed to them on a silver platter and make a name for themselves. Reincarnated and now donning new names and identities, they strive to eliminate all threats. One who commands the shadows, One who commands the void covered by the shiny reflection of ice, and another leaves the aftermath of nuclear power.

Shadow Garden of Fatui, who are they really?

I do not own Eminence in Shadow or Genshin Impact, none of the characters are mine and they belong to their respective owners.