Gelus was a shinigami who infatuated with a human girl on Earth, he would always watch her from the alternate dimension and would always talk about her. On the day that she was supposed to die, a crazed man was about to kill her because of his obsession. Gelus couldn't stand it and wrote the name of the serial killer to save her. He knew it would've killed him if he did it, but he didn't care, he did it in order to protect her. Due to it being against the rules he got turned into nothing, ending his life. As a result of sacrificing his life for Misa Amane, his Death Note became hers.