In a world without hope, in an age of dying dreams, some people will still find enough hope inside themselves to strive for the impossible. Shirou will attempt to bring light to his dark world, even if it is a fool's errand. (FSNxChangeling the Dreaming/WoD)

Angra Mainyu's almost-incarnation at the end of the Fourth War drew the attention of Zelretch - and the old meddler decided to involve a sort-of kin from another world who had some familiarity with the self-styled "source of all evil in the world".

Something went wrong when Shirou, Rin and Saber went to stop the Grail, and now they're running for their lives. Archer directs them to escape the dark sludge from the Grail through a hedge. A hedge full of thorns that seems to go on forever and fills them with strange thoughts. When they come out the other side, not even they are what they expect. (take idea if you wish)