In "The Guest," Daru is brave because he defies both the French authorities and the Algerians and allows the prisoner the existential choice of choosing his own fate.
Living on a lonely hillside, the schoolteacher Daru, who was born in Algeria, is not interested in the politics of the country, nor the fighting of the Arabs and the French colonials. When the Corsican gendarme, Balducci, brings the Arab prisoner to Daru, he does not want to be involved in transporting this man. Yet, although he is disgusted by the account of the Arab's petty violence--"Daru felt a sudden wrath against the man, against all men with their rotten spite"--he asks Balducci if the Arab is against the French. Balducci expresses doubt, but comments that one can never be sure. To Daru, therefore, there seems no sensible reason to turn him over to the French authorities.
The absurdity of the situation is characteristic of life. As an existential hero, then, Daru finds himself faced with choices that are both without sense. If he takes Daru to the Colonial authorities, his actions defy logic since the Arab has done nothing against the French. On the other hand, releasing him on his own recognizance infuriates the relatives of the murdered tribesman whose laws are different from that of the Colonial rule. So, Daru is brave to allow the Arab himself to make the choice of his own destiny. He is also courageous to act as a moral human being, a decision which, then, alienates him in an absurd world.