Halo: Eagle's Incantation

Shirou and Artoria vowed to reunite as starcrossed lovers; this was not what they had in mind. Being reborn for some inextricable reason, they are flung to the far future. A world where technology has advanced leaps and bounds, a world without a need for heroes. Regardless, history must march on, and Fate has quite an interest in making some new heroes...