Faust

Faust is the father of Tetsuro Hoshino and an old friend of Captain Harlock. He now serves as the chief servant of Queen Promecium, ruler of the Mechanization Empire. Tetsuro (and possibly his mother) believes Faust to be dead. Faust was once a warrior who fought alongside Harlock and Emeraldas, but at some point, his heart changed, and he took a machine body, becoming a high-ranking warrior of the machine people. After learning that his son is alive, he attempts to persuade Tetsuro, without disclosing his own identity, to see his point of view and cease opposing the Empire, knowing Promecium will otherwise require the boy's death. Tetsuro refuses, and he and Faust finally face off atop the 999 as Great Andromeda falls to ruin.
Despite the separate ways their paths have taken them and his sadness over seeing father pitted against son, Harlock still toasts Faust as a friend, knowing no matter who wins the battle, he will grieve the other's passing.