merem solomon's demon of the left arm
The Daemon of the Left Arm (左腕の悪魔, Hidariude no Akuma?), classified as the King of Rats (ネズミの王様, Nezumi no Ōsama?), is a daemon without any abilities related towards battle. He is the manifestation of Merem's wish to become others, the hope to transform, and he was designed after a friend of Merem who lived in the ceiling of his temple. He is a rat who is capable of transforming into anything that resembles the size and shape of a human, allowing him to act Merem's representative in human society under the guise of an elderly priest due to Merem being in the unaging form of a boy. It is his preferred persona despite his ability to transform into a myriad of people. He even acts as if he is Merem himself to all the other members of the Burial Agency besides Narbareck and Ciel because the organization values experience, with Merem believing that his true form would bring about unnecessary trouble. Ciel calls the priest "wise and cool" compared to Merem's more childlike personality. If ever brought under the gaze of a high-class exorcist, his facade will be undone and cause him to return to its original form.
Despite being intrinsically linked, they are not able to communicate telepathically. Should Merem leave the Left Arm behind with Narbareck, he must communicate with rats using his ability to speak to animals in order to relay messages. He is able to obtain information from them and relay messages to the Left Arm. They act reverently towards Merem, and consider the Left Arm to be the hero and idol of the rat world, thought of as the "third most beautiful rat in the world." He is popular in communities in narrow spaces underground, on ceiling boards, in drainage conduits, and behind furniture. Despite his fame, they often point out the contradiction in his status by asking "Just what part of you is a 'Great' Daemon Beast?", leaving him troubled while apologetically trying to think of an answer, or not. He is a cheese lover who likes humans because of pizza, and works daily at a relaxed pace for the sake of Merem, humans, and rats.
