I wonder what happened to make her go from a rebellious child to an ultra rule follower...I can see Ruby being quite judgemental of others (though more so in her own head than saying it out loud), but I wouldn't say she'd be the nastiest person in a room or a bully. Bullying involves social power and she's too weird for that lol.
I could be wrong though ofc. She once said that she used to be a wild/rebellious child, does anyone remember that? I wonder what that was like.