This is what Unknowns demon looks like, though they can shape themselves into whatever they want but they tend to stay in a human like form, Unknowns demon doesn't have a gender so their called they or it, they're always cold due to them being a shadow demon and being dead, this also makes Unknown cold but she is immune to it - she gets scared when she feels warmth - if its winter or cold enough for your breath to show if Unknowns breath shows its always black instead of white. It is in control of Unknowns powers if she is in control of her body and only allows her to do it when she needs to but if their in control they'll use them when they can 

Jesus they look creepy