Characters are what make a story. No characters, no story. For the most part–I am sure you could find some sort of experimental French novelist who proves me wrong, but let’s go with the mostly characters involved sorta stories. When we sit and write a story, we write it from the perspective of the people who are there for the whole story. Sometimes your character dies at the end, thank you Shakespeare, but for the most part your main character is the one who is there for most of the story.
Character death is important, just as a character needs a reason to exist, they should also have a reason to die. But I was going for realism you say. There is nothing wrong with realism. People die every day for lots of different reasons. Your story is not the real world. Just as we do not write dialog the way people really speak, we should not kill people the way they really die. The biggest thing with this is the shock factor. You know this death. Everything is going great, the trees are signing, birds flying, and then BANG, sniper from 1000 yards pops off one of your main characters. This is not to say that a sudden death is a bad thing, but when it does happen there are somethings you should keep in mind.
First is the setting. Have you established a setting where snipers are there and can shoot at 1000 yards? Another issue is timing. Why here? Why now? If you have established this setting throughout your story, then why was it at this moment that your character was offed?
The movie Jurassic Park II had a scene like I am talking about. Your two heroes take a spill over the cliff in their camper. The back-up character jumps in an SUV, ties off the trailer and starts to pull them up. In comes the T-Rex. There is this intense, and long, scene where the back-up guy is pulling up the heroes and dodging the dino. For these minutes you are cheering for him. Then as soon as the heroes are safe, he gets eaten. But that is real! You may be screaming. No, what would have been real would be the camper ditching over the cliff and the heroes dying. What the author did was make me care about this guy so that his death would have purpose. But it didn’t, it just increased dino-body count
Counter-example is in Aliens. As the marines are retreating and fighting off the wave of attackers, the floor opens up and an Alien grabs Hudson, an established character. He was a Marine. He was in battle. Marines die in battle. There is your realism.
When in the story your character dies is also important. Does the death further the plot? Ok, so what if you are sure that this the moment where your character dies. It is important here. Now, let’s talk about method. Sniper at 1000 yards? Why? If you are going for the shock death, then again I refer back to setting. If not, then could there be other ways? Just a normal firefight, with normal soldiers, instead of your super shot? Crash on getaway? Self Sacrifice? Why did you choose your method? Also, do not forget, if you are going for realism on your death, sometime people get killed, then you have to go for realism on your method too. If in your setting snipers who can hit things at 1000 yards are a dime a dozen, then go for it. And if you are so hitched on realism, how is your characters’ health? Could they have a heart attack? Stroke? What about being hit by a drunk driver? Asteroid? The method is as close to the plot as the death itself. If your character steps off the curb and gets hit with a bus, which is real, how does that move the plot? If they are being chased by someone (or something) and it gets the jump on them, does that time make sense? What about the previous story? Did your character survive a 70 ft fall in between spikes, but then later gets killed by a blow to the head?
So yes, Hamlet dies, Romeo and Juliet die, but did they die for a reason? The answer is yes. But my story is different. I know, they are all different. I am not trying to be Gospel. I am trying to make you think. When you kill off a character, is there a reason? A purpose?