Djinn

When a person forms a contract with a devil. The person exchanges their soul for power and charm. Most devils look for cadets (heroes in training) to form contracts with because their bodies have ample magic power and vigor, yet underdeveloped mental power. A regular human that forms a contract with a devil is called a Demi-Djinn, they have no intelligence and can follow simple tasks put on them, however they have no rationality and can be distracted from the task (e.g. Dog of Lucius).