In Camus' "The Guest," the Arab and Balducci represent two opposing forces in the life of our schoolmaster.

The main character in our story is Daru, a French Algerian schoolmaster—it is the night before the eruption of the Algerian War. This revolution is directed by the National Liberation Front (FLN). While it begins in October of 1954 (the setting for our story), it will continue to July of 1962—nine years—until the Algerians win their independence from the European influences brought on by the French colonization of Algeria.  

Balducci is a policeman who brings the Arab to Daru; because he is short on men, he asks Daru to assume his civic duty and transport the Arab prisoner to the authorities at Tinguit. Balducci is not an unkind man, but he is dedicated to his job. Following rules makes it easier for Balducci to see the world in blacks and whites, without his emotions getting in the way. 

"I'm going back to El Ameur. And you will deliver this fellow to Tinguit. He is expected at police headquarters."
Balducci was looking at Daru with a friendly little smile.
"What's this story?" asked the schoolmaster. "Are you pulling my leg?"
"No, son. Those are the orders."
"The orders? I'm not..." Daru hesitated, not wanting to hurt the Corsican.
"I mean, that's not my job."
"What! What's the meaning of that? In wartime people do all kinds of jobs."
"Then I'll wait for the declaration of war!"

Daru clearly does not want to get involved. Balducci, representing the law of the land, reminds Daru that when there is a war involved, everyone steps up to help. However, Daru does not ever come to the point where he feels comfortable taking the Arab to the jail.

Daru ultimately gets pieces of the history of this Arab prisoner, who is very quiet, resigned to his fate. Balducci explains...

He couldn't be kept at [El Ameur]. His village was beginning to stir; they wanted to take him back. 

The gendarme assures Daru that with this "errand" finished, Daru can return home and have not else to do with the war at hand.

You'll come back to your comfortable life.

Daru asks for details...

"...what did he do?"
"We had been looking for him for a month, but they were hiding him. He killed his cousin."
"Is he against us?"
"I don't think so..."
"Why did he kill?"
"A family squabble..."

In terms of the impending revolution, the Arab is no threat, it would seem, to Daru and Balducci. However, it does not mean that the arrangement does not come with complications. This is why the Arab and Balducci are so important to the story: the situation forces Daru to reflect on how far he is willing to go to support the European/French faction, and how sympathetic he will be toward the Arab.

Balducci leaves the Arab with Daru. Daru would like nothing better than to see the Arab run off, but the Arab is resigned to whatever awaits him. Daru finally walks the Arab to a place where the prisoner can either escape to the tribes who will protect him, or walk the rest of the way to the jail. Giving him money and provisions, Daru sends him on his way. Turning back, he sees the Arab walking to the jail. Daru cannot believe the Arab would not take the chance to save himself!

The Arab feels alone—and goes on to the jail. Returning home, Daru finds a threatening note because he "turned" the Arab over to the authorities—which he did not. Daru realizes that even without involvement in the war, he is isolated—no better off than the Arab: and an innocent victim.