He was old.
His name, once spoken with reverence across three continents, was now lost to the annals of time. He alone remembered, but spoke of it to no one. They would not believe Him, or would think Him mad, or joking, unless He displayed His power.
He was born - if such a being can be born - in the sands of what is now known as Afghanistan, born from the ideas of the tribes, trade routes carrying Him to Mesopotamia and beyond, gaining power as more worshipped his now-forgotten name.
Keeper of Life. Bringer of Death. Conductor of Pleasure. Divine of Inspiration. He was all of this, and more.
He liked to visit, now and then, when chance arose. Sometimes He spent a human lifetime wandering; other times, He chose a form and stayed, watching humanity change and grow. If He so willed, He would pass as human, until the time He decided to move on. His form would also change, to blend with any local population He was visiting, in the lands where He was once worshiped.
A voice called out to Him. Not a prayer, like those of ages past, but a call for aid. To provide. To be of use.
'JOHN! Pay attention! I need you to hold this liver!'
The being now known as 'John Watson' roused Himself from His reverie. He had work to do.