What are the attitudes between Daru and Balducci toard each other?  Is either a cruel or bad man?

In Camus' short story "The Guest," Balducci is a gendarme and a member of the European colonial powers that be.  He tells Daru his orders:

Those are the orders.

...In wartime people do all kinds of jobs.

...the orders exist and they concern you too. Things are brewing, it appears. There is talk of a forthcoming revolt. We are mobilized, in a way.

Since Daru is of European decent and not a native Arab, Balducci presupposes that Daru will carry out his orders and deliver the Arab to prison.

Daru tries to stay out of the decision whatsoever.  He feels he is a schoolteacher and schoolteachers should not be enlisted as marshals to deliver prisoners.  However, Daru fails to realize that he is complicit in the colonial power because he works for their educational system--an institution which wages cultural war on the Arabs as much as Balducci's armed forces.

Daru dislikes Balducci, but he is afraid to disobey his orders for fear of reprisal.  Balducci values "orders" above all, and sees Daru only as a means to an end.  Despite Daru's protest, Balducci knows that the schoolteacher is powerless to disobey him.

Daru feels Balducci is his guest because he feeds and harbors him.  Balducci thinks Daru is his guest because he outranks him.  Neither feel the Arabs are welcomed guests.  To the Arab, both colonists are certainly unwelcomed guests of his native country.