We see the emotions of guilt and remorse the sniper feels when he kills the old woman and the soldier in the street below his rooftop perch and again when the kills the sniper on the rooftop across the street (whom, at this point, he does not know is his brother). His reaction is to throw down his revolver as though he will never touch it again, which only causes the gun to fire and nearly results in him shooting himself in the head.
However, I don't think the sniper would go one to kill himself once he learns it is his brother dead in the street. Certainly, the rest of his life will be filled with guilt, remorse, and many other emotions. I think the more likely reaction is symbolized in the throwing down of the revolver. The sniper will walk away from the war, walk away from the scene, and re-invent himself in new life forever trying to understand and atone for his actions.
I believe personally, that the sniper understands--that war is difficult. You must learn to live with your choices--both the good and the bad ones. There is nothing to be done BUT move forward.
The reaction of sniper will depend very much on the conditions under which the brother is killed. One of the important issue is, whether the brother deserved to be killed for a valid and important reason. For example, if the brother was killed because he was a threat to national security, it is easier to justify his fate. Also, would the brother have been killed in any case by another sniper. Or would the brother have killed the sniper. The relationship between brothers and the basic nature of sniper will also be important. There are enough cases for one brother sacrificing his life for another. And perhaps equal number of cases of one brother killing another for personal gains.
I feel that he will regret that moment for the rest of his life, and to live with the fact knowing that he shot his brother is almost punishment enough. He must move forward by making sure actions like that do not happen again and educate the community on what actions like that mean to the community as a whole.
I think he is going to feel so bad that he is going to take his revolver out of his pocket and commit suicide or run out into the middle of the war and get himself killed. I think he would be feeling so bad after what he has done he wouldn't be able to confront his parents and tell them what he had done. He couldn't live his life, knowing that he had killed his own brother.
I think the sniper who shot his brother is going to give his own life feeling about his job and regreting pulling the trigger. And is scared of confronting his parents or other family with the bad news. It seems like he has such a kind and loving personality but he was there and he was going to a good job of his work. Now after going and seeing his brother dead on the ground he will not be able to take the war or the death of his brother.
It will be hard on him to carry on his life the way it was before this, but I think he will be able to. The fact that he killed his brother though will always be in his heart. I think that he is sad for the fact that he did kill his own brother. For him to have to tell his parents will be very hard on him but I think he will tell them the truth.
I think he would probably break down, maybe cry a little bit and hold his brother in his arms. Then, because he is so angry at himself, he will charge at the machine gunner while firing his pistol. Because he is so mad at himself, and does not want to go on living, knowing he killed his own brother, he decided to sacrifice his life.
The sniper would have to life his live knowing that he killed his brother, the person he grew up with, he killed. He would probably quit fighting in the army because he wouldn't be able to kill anyone anymore. He would have to tell his parents or maybe he wouldn't tell them because he felt so bad. And if he did tell his parents they might exile him from there lives. He might commit suicide because he couldn't live with himself or he might suffer from depression. He may end up living a successful life and not do any of the above but I think that in the back of his head he would still hate himself and never fully forgive himself for what he did to his brother and his family.
I think he felt a lot of remorse and he probably felt extremely sad, unless he had never known his brother or was not close. Another idea is that he might take his own life, if he does not however he might lie about the fact he killed his own brother. An example is that when he tells his family that his brother is dead; he would probably lie and tell them that he just saw his brother, and not that he shot him.