Mary and Matilda are twin demons who seem to have a positive relationship and VERY close bond, to the point where Mary will become violent if someone hurts or disrespects Matilda, and Matilda will become violently distressed when she's separated from Mary. They're quite innocent and naive and they become attached to people, often asking them to play. However, they have no conscience, thus have no concept of good and bad. People notice how insane the twins are and don't play with them.