Who is Rainer Moerling Hartheim from the novel, The Thorn Birds?

Rainer is a young German soldier, an orphan from Bavaria, when Father de Bricassart first meets him at the Vatican. The young man is traumatized by the war, and terrified the Germans will decide he has Jewish blood because of his dark coloring. After the war, Rainer becomes a German cabinet minister, confidant of Cardinal de Bricassart, close friend and eventual husband of Justine O'Neill. After the Cardinal's death, Hartheim is appointed administrator of Mary Carson's estate, including Drogheda, a fact he conceals from the Cleary family.