Six

I love this little nightmare (pun fully intended); she's such a strange character and its not fully explained who she is, and that just makes her more interesting to me.
I have a few ideas about Little Nightmares. Heads up, spoilers
I'm not fully sure if I think Six is the child of the Lady. The little comic about her shows that she was brought to the Maw from the city for some reason (possibly for being a child) by another person; if she was the child of the Lady, she would already be living on the Maw and not be wandering around in the city. So, I have a feeling that in the world Six lives, childhood or children are seen as 'illegal' and are sent to the Maw for imprisonment and eventually death. It's possible that the Lady has some control over the illegal-ness of children, since she could be trying to rid the world of anyone more beautiful than her and needs a way to get rid of any children who could grow up to be more beautiful than her while she's killing the adults in the world.
I dunno, those are just my thoughts!