So, the general backstory for this character is that she was raised by birds of some sort. Is it legit to have her AU backstory be something like "disappeared in the woods as a child and emerged years later, claims to have been raised by the birds but no strong evidence other than her behavior"? Would I need to flesh out what "actually happened" or would it be okay to leave this as something vague for you to play around with?

Also, in modern AUs I generally have her almost completely nonverbal and using a communication app with simplified grammar. Would that work in this setting?

Also, a less related question, are nonbinary characters who use a male PB allowed?

EDIT: Another silly little question, would it be kosher to add staff NPCs who are AUs of my own characters/OCs?