For your Speak of the Devil au,
Does Shadow know who Maria is?
He does! Maria was Shadow's closest and honestly only friend before he got captured and tortured. I can't remember exactly how much I've shared on Tumblr about this bit of the lore, so I'll just give a quick rundown! The world of Speak of the Devil is split into the Higher World (where the Angels live), the Middle World (where the Mortals live), and the Lower World (where the Demons live). Angels have long since stopped venturing out from the Higher World but Shadow was curious and decided to go explore the Middle World one day. It was Maria who befriended him and showed him around.
Shadow hasn't seen Maria since he was captured and doesn't know where she is. Aside from staying safe, that's Shadow's big goal in the AU. Finding Maria.