The Darkness is a supernatural being that requires a human host. It is unable to reveal itself until it's host is 21, having gatherd enough power to make its appearance.
The Darkness is able to speak directly too and shares its powers with the host. Its powers include tendrils, two demonic heart devouring heads, a black hole, and imp like creatures called 'darklings'. The darkness has a weakness to light and cannot manifest in bright areas.
The Darkness is it's own being with a strong will to control it's host and not be controled by the host. Control over the darkness can only be achived by the host commiting suicide and making thier way through hell/the darkness's mind. The darkness will lie, lead it's host astray, and revive them every time they die.