Keanu Fallwind is one of the main villains of the Wild Arms: Twilight Venom anime series.
Keanu's original incarnation was that of a soldier serving the Earth forces during Fargaia's rebellion 10,000 local years ago. Instead of suppressing the rebellion, however, he became sympathetic with their cause and the plight of the planet itself. He intended to try to reason with his lover, Laila, in an attempt to end the blockade and abandon the war. Unfortunately, she mistook his overtures as an admission of infidelity and shot him, mortally wounding him. In her insanity, she also launched the Twilight Venom onto the planet, devastating it.
Laila was not finished with her love, however. She modified Fargaia's terraforming process in order to reincarnate both herself and Keanu in a future era. The reincarnated forms would meet, though without their previous memories, as Gina Angel and Sheyenne Rainstorm.
When the organization ROOF learned of Laila and Sheyenne's reincarnation, they immediately sought to use them to secure their power over the world, with Laila as their goddess, and clones of Keanu (a rare ARMS user) serving as their soldiers.
Sheyenne's actual brain was removed and put into a body of a cloned boy, while the original body was given a new body and programmed with the artificial memories of the legend of the original Keanu. Keanu and the now-child Sheyenne would eventually fight for both the love of Gina (who had been crudely brainwashed into believing she was really the original Laila) and for the body itself.
When the cloned Keanu learned the truth of his existence, he destroyed himself in a final act of spite against Sheyenne, Laila, and ROOF, using the upgrade module of the Bator to destroy his own head. Ironically, this act actually freed both Sheyenne and Gina to live their own lives - once they destroyed the Twilight Venom, of course.