Liam O'Flaherty's sniper, from the short story "The Sniper", is both calculating and remorseful.
In the beginning, the sniper desires nothing more than to take out the sniper on the other rooftop. The quote "He must kill that enemy" shows his admittance towards his desire to do what ever needs to be done to dispose of the threat. He devises a plan to lure the other sniper out into the open so as to be able to find a certain kill shot.
The sniper, in the end, changes dramatically. Instead of his desire laying in the kill, his desire suddenly changes. After he makes the kill, the sniper is "became bitten by remorse." His whole attitude about the job, his job, at hand (given now completed) has forced him to rethink his position. He is no longer filled with the desire to kill. Instead, "the lust of battle died in him."