The Shader Clan

They fuel themselves through the blood and nutrients of their host, but offer increased intelligence and processing power to those who are willing to accept them. They were usually used to help those with brain issues, but they spread out of control once they were given the ability to reproduce.
They turn their host's eyes red.

Their ranks are nearly unending, and most of them consist of machines who have taken over organic bodies.
They view humans as better than them, so they steal their bodies. The process is extremely painful for the host and will put them into a three day coma to recover.