When he and his comrades fell, they found that hell was a barren land incapable of supporting life of any kind, so he rooted his body to Hell's ground, merging with it in order to make Hell habitable. Thus when Hell's earth breaks, it is his blood that gushes out. He later returns to Eden a second time to free Alexiel from her God-made prison, and thus assisted in bringing forth the second rebellion, which Alexiel staged.
As his punishment for assisting Alexiel's escape from Eden, God extracts his soul and imprisons it in a seven-bladed sword, Nanatsusaya Mitamanatsurugi. His soul was imprisoned in the sword for so long, he forgot all his memories. A number of people tried to wield the sword and failed until Alexiel came along. He allowed her to control him, because she was the woman that held all his memories in her hand. As Nanatsusaya, Lucifer hated Alexiel because he was helpless as she knew more about him than he did and she would never reveal his past to him. But when Alexiel was captured by the angels and sealed in the Angel Crystal, Nanatsusaya followed her through all her reincarnations. He deludes himself into thinking that it is because he hates her and wants to see her suffer, but in the end his actions prove otherwise.
He later helps Setsuna defeat YHWH