The Red Maid by Derek Strohm

In London, England, there are crimes that the police sometimes can't fix. That's where Jake, and his maid, Talia, come in. The duo help fight crime throughout the city.Talia is a half-demon. She got kidnapped by exorcists and forced to have a demon fused into her body, giving her super speed, reflexes, and vision.The police have been reporting various people doing superhuman traits, and Jake and Talia have found out the criminals were demons, three of them, led by the many-faced cerial killer, Hybrid, who is also a demon. Talia confirms that Hybrid has the power to get the demon out of her, so they have to find him, and defeat him, before the demon inside of Talia, the Red Maid, kills her.