Resident Evil 9: Requiem was initially developed under director Hiroshi Nakanishi with an online gameplay focus. Midway through development, unfavorable research results led the team to abandon this approach and refocus on delivering a horror experience. Producer Tsuyoshi Kawata reflected on this shift in a developer interview featured in the series' 30th-anniversary special edition.
Kawata also discussed the dual-protagonist setup. Leon was the first protagonist confirmed, but the team felt that focusing solely on him, who excels in combat, would make zombie encounters too easy for players, shifting the game toward action and diminishing its horror elements. To address this, the developers introduced a new character, Grace, allowing the game to balance both horror and action aspects.
Kawata stated that the team had also considered withholding full details about Leon's involvement until a later stage to maintain player interest in the overall scope of the game.