Enjou, Tomoe

In the middle of October 1998, he was attacked by bullies from his old school and saved by Ryougi Shiki. He asked her to hide him at her place and admitted that he had killed his parents because of constant dreams of getting killed by his mother. The origin that he has is "worthlessness."

[Spoiler] In the end, he was actually a puppet of Enjou Tomoe, the real Enjou Tomoe was already dead. This puppet was made by Araya Souren in one of his experiments that attempted to create the gate to the Spiral of Origin.

The puppet, however, was able to escape from the loop in which he was killed at night and reborn in the morning. He was attracted to Ryougi Shiki, fell in love with her and he even confessed (although Shiki only reacted by laughing at him). It is unknown whether his attraction to Shiki was because of his own feelings, or because Araya Souren added it as unconscious imprinting when he ran away. [/Spoiler]

(Source: TYPE-MOON Wikia)