Dramatical Murder - Season 1 Episode 12 Data_12_Dawn

As Ren's memories pour inside Aoba's mind, Aoba uses Scrap on himself in order to speak with him. Aoba sees that Ren is falling apart due to the worm. Ren reveals he was originally a part of Aoba's consciousness, his "restraint" that was created to monitor his "desire" (the other Aoba) so that it wouldn't take control of him. However, there was a period of time when Aoba's "desire" took hold of him and Ren could no longer influence him from inside his mind, prompting him to transfer his consciousness into the Allmate's dog body when Aoba discovered it. As a physical being, Ren was able to influence Aoba more easily, but because of Virus and Trip tampering with Aoba's memory in the past, Ren had forgotten his original purpose until the worm infected him.