How does "The Guest" relate to one's response to the constraints of convention or circumstances?
I think the situation depicted in the story has more to do with circumstance than to convention. Daru is given the responsibility of escorting the Arab to town, where he will be "tried" and most likely convicted. Because his schoolhouse is isolated and not part of any village, there is no one else to take on that duty instead of him. His initial response is to refuse, but Balducci doesn't give him much of a choice. Even though he does take on the job of guarding the Arab, Daru does his best to allow the man to escape. Perhaps if Daru's circumstances had been different, he might have reacted differently when he left the Arab on the crossroads. If the area had not been so isolated, if there had been many people around, Daru might have been afraid to let the Arab choose his own destination. Maybe Daru wouldn't have been so brave if he knew someone might report him. On the other hand, if his schoolhouse were not so isolated, he'd have more protection from the Arab's friends, who wrote a warning on his chalkboard.