Concept and creation
The original concept for Final Fantasy VII's world was for a fully modern setting, but after the project moved from the 2D Super Nintendo Entertainment System to development for the PlayStation console, the setting altered with it. Elements from the original concept were later used in Final Fantasy VIII and Parasite Eve. The game's producer, Hironobu Sakaguchi, chose character designer Tetsuya Nomura to create the main cast. Nomura had previously worked on monster designs for Final Fantasy VI. Sakaguchi chose Nomura after being amused by the way Nomura did the storyboarding for the cutscenes. Talking of his role as character designer, Nomura stated that when he was brought on, the main scenario had not been completed, but he "went along like, 'I guess first off you need a hero and a heroine', and from there drew the designs while thinking up details about the characters. After [he'd] done the hero and heroine, [he] carried on drawing by thinking what kind of characters would be interesting to have. When [he] handed over the designs [he'd] tell people the character details [he'd] thought up, or write them down on a separate sheet of paper." Nomura also created Zack Fair, who was a late addition to the cast meant to add depth to Cloud and Aerith's relationship, and came up with the name for Red XIII, wanting an "interesting" name that combined a color and a number. Although the game was Nomura's favorite Final Fantasy project, he felt that it was hindered by graphical limitations, and that his designs were, consequently, very plain in comparison to his "true" style.
The game's plot was created by Sakaguchi, although the majority of scenario writing was done by Yoshinori Kitase and Kazushige Nojima, who conceived of the Shinra plot thread, Cloud and Sephiroth's relationship and Cloud's backstory. The Lifestream, the source of life for the planet, was one of the earliest concepts created for VII, but its depiction and purpose changed drastically during development. The concepts behind the Lifestream and Aerith's iconic death scene were sparked in Sakaguchi by the death of his mother, which inspired a wish to create a realistic death for Aerith rather than a "Hollywood" sacrificial death. The "dark" theme described by Nomura is continued throughout the Compilation, with characters such as Kadaj, Loz and Yazoo in Final Fantasy VII: Advent Children and the Tsviets in Dirge of Cerberus: Final Fantasy VII. Producer Yoshinori Kitase stated that voice acting was one of the topics to which the Compilation team paid close attention. As Cloud and Vincent have similar personalities, care was taken to differentiate between them and their dialogue. The compilation was originally conceived as only one title (Advent Children), which focused on Tifa and Cloud, but they eventually expanded it into a collection which included other games focusing on other characters, such as Zack and Vincent. Nomura himself requested Hajime Tabata, the director of Before Crisis, to create a game focusing on the Turks.