Naraku was a human thief named, Onigumo. He was seriously burned and couldn't move. Kikyou found him and took care of him. He began to have twisted desires for her and wanted a new body. So he offered his body to hundreds of demons to eat. They all joined to become the new and improved Naraku. After Naraku was born, he was jealous of Inuyasha and Kikyou's relationship. He attacked Kikyou in Inuyasha likeness, leaving her with a fatal wound. He then attacked Inuyasha in Kikyou likeness. His plan was to make Kikyou and Inuyasha believed that they were betrayed by the other, and to have Kikyou kills Inuyasha with her own hand. He thought that Kikyou would then use the jewel to save herself. Inuyasha will be out of the picture, and he will have both Kikyou and the jewel for himself. Of course, things didn't go as he planned. Kikyou chose to die and took the jewel with her. That left him with nothing (poor Naraku). 50 years later, he found out that the jewel has returned, so he's now on a mission to get it again and making life a living hell for everybody else. He later found out that the real Kikyou was brought back to life. He loves her, he hates her, he's afraid of her spiritual powers. He wanted to kill her, but couldn't hurt her because of his human heart (talk about a thin line between love and hate). So he is searching for ways to get rid of his human heart and all that unnecessary feelings for Kikyou.