Artorias ends up in Westeros after his defeat at the hands of the Chosen Undead. How will the events of ASOIAF change with Artorias the Abysswalker in it?

The fire fades, summer ends, and the long night approaches. Perhaps it is already here. Voices and screams. Flickers of memory. A task undertaken, and a promise unfulfilled. Even now, only embers remain. And so it is. That ash seeketh embers. (Fusion AU)