Four years after the death of Neil Dylandy, Setsuna F Seiei recruits Neil's twin brother, Lyle, to become the new Lockon Stratos and pilot of the Cherudim Gundam. He is shown to be easy-going like his brother, but continues to struggle with distinguishing himself from Neil. Originally a member of anti-government organization Katharon, Lyle joins Celestial Being for his own reasons.