The vassal stuck in twisted sense of responsibility
Ciel feels great demonic energy and the changes in his body following the second soul contract and receiving most of Lu's soul. When Lu's emotions fade away after the contract, Ciel believes this to be his fault. He continues the investigation by brutally slaying the demons to find more clues about the soul contract, but could not find anything. As Lu's condition begins to worsen, Ciel's self-blame and guilt begins to settle in a twisted sense of responsibilities and, with powerful demonic energy, manifests as EGO.