Liam O'Flaherty's short story "The Sniper," a sniper for the Republican Army is posted on top of a building, trying to insure the forward movement of the Republicans over the Free State. The sniper is confident in his talents and power.
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.
Here, the sniper is defined as a fanatic. The fact that he is described as a student shows his openness to learning, knowing that every situation he is in offers a deeper understanding of his craft. Given that he has seen much death, he is far from a squeamish man. Instead, he is calculated (shown by the drag he takes on his cigarette) and focused (given the time spent on the rooftop). His excitement is also noteworthy (given he has been unable to eat because of his excitement).
It is not until the sniper takes out the Free State sniper that his humanity is shown. Over the course of the story, death is simply a part of his job. While the sniper's return to humanity is masked, one could assume that his humanity returns upon his "sudden curiosity as to the identity of the enemy sniper." Something was drawing him to the body.
Upon turning the body over, the sniper realizes that it belongs to his brother. Therefore, while the return to humanity is concealed, given the story ends here, one can only assume that his hardened persona is shattered by this realization.