Mother

• Demon who tried to take over the world through modifying magically exceptional subjects into weapons of mass destruction
• Behind a secret government agency
• Unable to exist in the mortal plane because the way mother moves is distorted and physically impossible
• Inhabits a robot body
• Defeated by Saffire

Mother is a demon whose come to this dimension to conquer and claim it. Mother is unable to physically enter the mortal plane, as mothers body does not obey the laws of physics of this dimension. Mother infiltrates the mind of a federal government worker named Caine, and he forms a high-up organization of researchers to aide in Mothers cause. A robotic body is made for Mother to inhabit this plane, and subjects with powerful souls are being abducted and experimented on, in hopes that Mother can turn them into godly weapons to ravage this plane.
Mother commands a demon follower called Center to fuse with an insanely powerful soul that was about to be born, hoping to create the ultimate weapon. The angel Radienccee split the child Saffire's soul in two, and fusing with half to form The Malice of Saffire (Mal-Saf), while center fused with the other half. This left Saffire much more mortal and less powerful, and Mal-Saf's angelic body was completely unalterable, making them impossible to fuse back with Saffire's or experiment on otherwise, making him useless to Mother. However, Saffire becomes incredibly mentally and magically unstable when apart from Mal-Saf, so the facility must keep them together and create The Gemini Project in hopes of eventually finding a way to re-fuse them and create the ultimate being who is mortal, demonic, and angelic.
Mother oversees Saffire's development for years, and grows unsatisfied. Mother plans to separate the twins, to preform extreme magical experiments on mal-saf and put Saffire into a temporary coma. This is interrupted by the medical scientist overseeing Saffire, Jada, warning the twins and allowing them to protect themselves. Mothers plans are overthrown, leading mother to enact her revenge on Jada by turning her into Mistress and forcing her to fight core subjects.
Eventually the core subjects revolt, and Mothers best attempt to stop this was to rip mal-Saf's soul from the angels, mortally wounding them. Saffire blacks out when Mal-Saf's life is in danger, and makes a deal with her demon that Saffire would rejoin souls with mal-saf, and the demon could have Saffire's body as long as it killed Mother. The demon takes Saffire's body and kills mother, but Saffire's soul left if Mal-Saf's body is much more powerful. Part of it stays in Mal-Saf's body, just narrowly saving her life, and part rejoins the demon in Saffire's body, and is now weaker to it. But Mother is dead, and the subjects have escaped.