The World is for the Two of Us - S1.E21

Altair incorporates Sirius into herself and overpowers the other Creations, bringing the world to the brink of The Great Destruction! Meteora and the others try to save the world by making Setsuna Shimazaki, Altair's Creator and their last hope, appear in the world. Altair and Setsuna encounter each others as Creations in the same world, and begin to reveal their true feelings to each other.