In Children of Dune, Farad'n is the grandson and heir to the deposed 81st Padishah Emperor Shaddam Corrino IV; his mother is Shaddam's third daughter Princess Wensicia, and his deceased father Dalak is noted to be related to Count Hasimir Fenring, a close friend of Shaddam's since childhood. Shaddam and most of his family are exiled to Salusa Secundus after he is deposed by Paul Atreides in Dune (1965).
As the novel begins, Shaddam is dead and Wensicia plots from exile to restore House Corrino to its former glory and wrest control of the Empire for Farad'n. She attempts to assassinate Leto II and Ghanima Atreides, the heirs to deceased Emperor Paul Atreides, by sending mechanically-controlled Laza tigers to hunt them in the desert. Leto's growing prescience allows him to thwart the attack on himself and his twin sister; he pretends to be dead to escape the increasingly murderous ambitions of his father's sister Alia. Farad'n — newly-trained in the Bene Gesserit ways by Paul and Alia's mother Lady Jessica — accepts an arrangement brokered by Jessica for him to marry Ghanima and share the throne; his part of the deal is to "denounce and banish" Wensicia for Leto's murder attempt, which he does.
Having used self-hypnosis to actually believe Leto had been killed and thus avoid discovery by Bene Gesserit Truthsayers, Ghanima vows to kill Farad'n for masterminding Leto's murder. Leto reappears, now beginning the transformation into a human-sandworm hybrid, and ascends the throne himself. Leto commands Farad'n to be Ghanima's mate, fathering the future Atreides line as Leto himself is now physically unable to sire children. Farad'n is also appointed as the Royal Scribe and renamed "Harq al'Ada" (the "breaker of habit"), and relinquishes his control of the Sardaukar to Leto, effectively surrendering House Corrino's claim to the Imperial throne.
Many of the chapter epigraphs in the novel are from the later writings of Farad'n (as Harq al'Ada) in his role as Royal Scribe, chronicler of the reign of Leto II.
Read more about this topic: Farad'n Corrino