The Thirteen Angels series was a AU Final Fantasy XIII-Final Fantasy VII Crossover fanfiction series that introduces as the world of Pulse and Gaea being nothing more than alternate dimensions, two sides of the coin linked by Valhalla and the Lifestream, it is Authored by AbyssKeeper and Co-Authored by HubrisP, it introduces Jenova's species and the return of Sephiroth to fight beside Lightning in her quest to stop Villains destroying Pulse itself.