In a recent interview that was included in Making of Fire Emblem: 25 Years of Development Secrets, Super Smash Bros. creator Masahiro Sakurai discussed the details of how Roy became a playable character in Melee before his game, Fire Emblem: The Binding Blade, was released in Japan, as well as other details about Roy’s inclusion in Smash. According to Sakurai, Roy debuting in Melee was not the plan from the beginning; initially, The Binding Blade was supposed to release before Melee, but it ended up going through some changes in development that delayed it.
Sakurai also stated that, after hearing the first description of Roy’s character, he saw him as “a bit more energetic” than Marth, with “a bit more strength inside of him.” This led him to design Roy’s moveset with a sword that was stronger near the hilt, rather than being stronger at the tip like Marth’s. However, he felt that, after playing The Binding Blade, Roy’s actual personality was nothing like what he had envisioned; Sakurai wanted to “make it clear [that] his representation in Melee is not because [he] didn’t understand his character.“
Sakurai also discussed the development process for Roy’s latest appearance in Super Smash Bros. for Wii U and 3DS; he stated that he had Roy hold his sword with a reverse grip sometimes because he “thought that would strengthen the image of him getting close to his opponent and hitting them with a lot of power.” When he started designing Roy’s DLC, he used Melee’s design as a starting point and remade several aspects of the character to differentiate him from the other Fire Emblem characters that were already included on the roster; he didn’t want him to just be a simple clone.