In this short story, the Irish Republican sniper is stationed on a rooftop overlooking the beleaguered Four Courts and must use his wits to outsmart and kill the enemy sniper on the opposite roof. O’Flaherty describes the Republican sniper by writing,

"His face was the face of a student, thin and ascetic, but his eyes had the cold gleam of the fanatic. They were deep and thoughtful, the eyes of a man who is used to looking at death."

Given O'Flaherty's description, the sniper is depicted as an enthusiastic young man, who has seen too much and has become desensitized to violence. The Irish Civil War has hardened the sniper's heart and transformed him into a calculating killer. The sniper displays his callous, dangerous personality by shooting and killing an informant as well as a solider in an armored car. The sniper's ability to hit targets from long-range depicts him as an experienced, skillful marksman.

Once the sniper is shot in his forearm, he demonstrates his tough, fearless personality by gritting his teeth, cleaning the wound, and bandaging the area. The sniper also proves that he is skillful, intelligent, and inventive by creating a successful ruse, which fools the enemy sniper and gives him the opportunity to take a clean shot. After the sniper kills his enemy, O'Flaherty writes,

"The lust of battle died in him. He became bitten by remorse. The sweat stood out in beads on his forehead. Weakened by his wound and the long summer day of fasting and watching on the roof, he revolted from the sight of the shattered mass of his dead enemy. His teeth chattered, he began to gibber to himself, cursing the war, cursing himself, cursing everybody."

The sniper's response depicts him as a remorseful, guilt-ridden young man, who is sick of violence and destruction. War has traumatized the sniper, who struggles to accept the duality of his human nature. Although the Republican sniper is a compassionate human, he is also a heartless killing machine at times. The war has forced the sniper to remain callous, insensitive, and violent to survive. The sniper has suppressed his humanity, which comes to the surface after killing his enemy, which turns out to be his brother.

The short story "The Sniper" by Liam O'Flaherty tells of a young Republican sniper stationed on a rooftop near O'Connell Bridge in Dublin, Ireland. He eats a sandwich, drinks some whiskey, and then lights a cigarette. However, the flash of the match draws fire from another sniper.

The protagonist shoots the driver of an armored car and a woman informer, and then the other sniper shoots him in the arm. He dresses the bullet wound as best he can. When he is done, he executes a plan to trick the other sniper. He drops his rifle to the street and lets his left arm hang as if he is lifeless. His adversary shows himself, and the sniper shoots him with a revolver so that he falls off the roof and dies. When he goes down to the street and turns the body over, he realizes that he has just killed his brother.

There are numerous clues in this story as to the character traits of the sniper. In appearance he is like a student, but his expression is that of a fanatic. He is obviously dedicated to his cause. He has seen death before, but he is courageous in the face of it. War and death have made him callous enough so that he is even willing to shoot an old woman if he thinks that she is on the enemy's side. He perseveres despite great pain, and he has the resilience and steadiness to tend to his wound even though the pain of the iodine is almost overwhelming. He shows his resourcefulness and intelligence in coming up with a plan to distract and kill the other sniper, even though he has a great disadvantage due to his injury.

The flaw that besets him is the same as all the fighters in that terrible conflict: they are warring against their own countrymen and even their own relatives.

The sniper is depicted as having the face of a student, who is thin, ascetic, and has a gleam in his eyes that suggests he is a fanatic. Although he is a young man, his eyes are also deep and thoughtful as if he is used to looking at death. Throughout the course of the short story, the sniper demonstrates his expert marksmanship skills by killing an enemy in the turret of an armored car and an old woman acting as an informant.

After being shot in the forearm by an enemy sniper, the protagonist sniper demonstrates his toughness and focus by wrapping his painful wound and formulating a plan to avoid the enemy sniper stationed on the opposite rooftop. The sniper's rouse reveals that he is resourceful, intuitive, and creative. The young sniper's reaction following his successful kill implies that he is stressed out and completely exhausted from fighting. The fact that he throws his loaded weapon against the ground and gibbers to himself reveals that he is a sensitive, rather reckless individual who is dramatically affected by the constant death surrounding him. His motivation to look into the face of the enemy sniper at the end of the story also reveals that he is a curious, inquisitive young man.

The narrator says that the sniper has "the face of a student, thin and ascetic, but his eyes had the cold gleam of the fanatic." He is, or at least looks like, a student. So, he has a youthful appearance. Ascetic means that he is serious and has self-discipline. Although he has this youthful appearance and a spirit of innocence, he now has a cold gleam in his eyes. Once young and innocent, he is now "used to looking at death." 

So, the sniper is a disciplined, serious soldier who is accustomed to war. He is almost like a machine in his efforts to kill the enemy and keep himself alive. However, that youthful innocence (and his humanity) does resurface when he watches the enemy sniper fall to the ground. "His teeth chattered, he began to gibber to himself, cursing the war, cursing himself, cursing everybody." He shows two clear sides to his character: that of the mechanical, efficient soldier and that of the compassionate human being. Being in a war zone, he must let the soldier side dominate in order for him to survive.