Disclaimer: I don't own Naruto.
To Tenten, killing is something that can be beautiful if you let it.
On the battlefield, there is a certain song that plays and sings in the mind of listeners who have the ears to hear it, but only at a certain pitch. Those who are trying to seek it will never find it, and the song often comes up on its listeners unawares. It's a blood song, high and lively, and throbbing with life in all its vicissitudes and wonders.
It comes in the high tide of battle, when the violence has peaked and can rise no more, when the blood is rushing in and out of veins and bodies, when individual thought in the mind of the fighter is replaced by sheer animal instinct and impulse.
Tenten lives for the song, and for the different song that comes upon the death of a soldier. It is a different tone, something deeper and darker, filling her with numb satisfaction that doesn't lead to nausea in her as it does in others.
And that, more than anything, makes her think that, if it's done right, killing can be beautiful.
.x.X.x.
To Baki, killing is sometimes required.
Each hidden village has its own way of disposing of traitors. Konoha opts for a quick beheading; Kumo has them hanged, their rotting corpses adorning various designated bridges and gates in the village. Iwa has their traitors lined up blindfolded and marched out in front of a firing squad of archers; Kiri drowns them.
In Suna, it's somewhat different.
Solidarity and loyalty to one's village are qualities taken very seriously in the desert. Anything other than a tight ship could potentially prove the ruin of Sunagakure, so treachery tends to be looked at askance. Extremely askance.
A convicted traitor is not given a chance to repent and reform; they knew what they were doing when they tried to sell their village out, and Baki has absolutely no pity on them.
In Suna, a convicted traitor is condemned out onto the dunes after having his hands cut off at the wrists (the wounds are cauterized of course; bleeding to death would be far too quick) and having his eyes gouged out. They are usually dead within hours.
Baki, by virtue of his high rank, is often called upon to perform this grisly task. He knows that though what he does is not strictly killing, whomever he does this to will die as a result of his actions.
But he doesn't lose much sleep over it. After all, the ones he killed would have seen his village burn to the ground, so retribution is just and deserved.
.x.X.x.
To Haku, killing is undesirable.
Haku is a peaceable person who only ever feels anything closer to murderous when her precious people are threatened. She had her fill of killing (even accidental killing) when she was young, and she does not wish to kill again.
But at the same time, Haku is Zabuza's tool. He's going to retake Kiri someday, and when he does he will need her to kill his enemies. Thus the need for practice.
Haku does not like to kill, and spares more people than she kills; Zabuza calls her soft, but with an oddly gentle tone of voice. But she will kill, for Zabuza's sake, if no one else's.
.x.X.x.
To Sasori, killing is an art form.
There's nothing to it concerning pleasure or repulsion. It's an art; it's to be treated with a distant respect (The ardent, devoted, too-closer respect is better reserved for Deidara and his brand of shoddy imitation art).
Art is supposed to be somewhat cold, because too much heat can warp wood (and Sasori doesn't want that), and a body always goes cold after the life has been drained out of it, so a blank chill settling over a field after battle doesn't bother Sasori, even if he was born in the fiery desert wastes of Kaze no Kuni.
Sasori is cold too, but after all, he's already died in so many ways, that the settling chill on his puppet bones is just another form of art.
.x.X.x.
To Shizune, killing is just a job. It's not something particularly pleasant, but it's not so appalling that she refuses to do what is required of her.
Shizune will not deny it if it is said that she is masterful at meting out death. She is a blooded kunoichi; she has always known that her life would be spent delivering souls into the clammy arms of Death before their time, if she chose to become a soldier, and she does not regret it.
She does not regret it, because if any innocent person has ever suffered because of her job, she does not know their faces.
.x.X.x.
There are many misconceptions about why Gaara kills. Many assume that he kills because he is a schizophrenic psychopath, and that he simply does not connect death with sin. Others look at him and choose to see an inbred sadism that thirsts for blood beyond all human longing. A different view, usually espoused by the insane and the demented, is that Gaara is some sort of terrifying, crimson parody of an avenging angel. Another view, the one closest to the truth, is that the influence of the Shukaku upon his child's mind warped his sense of right and wrong and twisted him beyond humanity.
All are very good guesses, and all are very wrong guesses.
Gaara kills to appease Mother. Mother is that voice in the back of his mind, far more guttural and scratchy than any human woman's ever could be. It is the threatening, terrifying voice that promises him exquisitely drawn out torture if he does not do exactly what she says.
Mother tells him to kill, and tells him that if he does, she will leave him alone for a little time, until her bloodlust rises again.
And Gaara does as he is told. After all, it's all to please Mother, isn't it?
.x.X.x.
To Anko, killing is a high.
Killing is to her as heroin is to an addict, the only thing capable of stemming the horrific, earth-shattering pain deep within her veins and blood vessels. It's a dirty, sinful thing, and she loves it for being her not-so-secret vice.
It's no secret that among shinobi communities, one of the first signs of madness is considered an undue desire to kill, an undue pleasure in killing. Taking too much pleasure in murdering and slaying is seen as wrong, is looked upon with wary eyes like deer ready to take flight.
Anko knows that it is aberrant and abnormal to display such ardent pleasure in killing as she does, that she is looked upon by her fellows (with the exception of Morino Ibiki, just as mired in sadism and madness as she) as being slightly mad, and that even more chalk her inherent sadism and cruelty up to her time with the bloodthirsty Orochimaru, but she'd be lying if she were to say she cares.
Death is Anko's high, and as long as she is a kunoichi, there will be plenty of highs to be had, and plenty of ways to sate her fluctuating insatiable bloodlust.
.x.X.x.
To Jiraiya, killing is an unpleasant task.
Jiraiya fought in the Second and Third Wars, the latter of whom was the most violent conflict to ever splash blood and brain matter across the five nations, and lost his parents to the First when he was just a small child.
War is a brutal reality; the only ones who ever win are the carrion crows, and even then it's only the carrion crows who get to the battlefield first who win. Jiraiya is weary of war, of what it does to people, of what it has done to his comrades.
Sakumo and Minato are both dead thanks to it, and Jiraiya is helpless to do anything but watch as Tsunade dies in little ways thanks to the price killing has exacted over her.
Jiraiya values peace, not because of what war and killing has done to him, but because of what it has done to his loved ones. He doesn't like to kill because it's going to do something to someone someone else cares about, maybe even be the death of someone, the way Tsunade lost Dan and Nawaki, and Minato's student Kakashi lost his father.
What makes killing so repellent to Jiraiya is his unfortunate—unfortunate in the eyes of the shinobi world at large, not to himself—tendency to think too much. Think about what killing some random soldier is going to do to that soldier's family.
.x.X.x.
To Itachi, killing is just a means to an end, and is something that must never be enjoyed, no matter how much the target deserves it.
In an ideal world, Itachi would not have to kill anyone. His family would still be alive, he would not run with a rabble of S-Class criminals, and he would still be living in Konoha with his little brother.
But Itachi does not live in an ideal world, and he does what he must.
Itachi rarely kills; he values life much more than he does the concepts of ruthlessness and mercilessness. But when he does, he makes it quick and painless, over in an instant, so that the accusing eyes and anguished gurgles of his victim will not haunt him too terribly when falls to his restless sleep.
And when he kills, Itachi thinks of all the children whom he smothered in their children's dreams the night he was ordered to massacre the clan. Itachi thinks of the brother whom he did not kill but instead destroyed, and he is ashamed.
.x.X.x.
Choji decides that he does not like killing.
This sets him apart from most of his colleagues and comrades. True, few shinobi live for the kill and revel in it the way one of questionable sanity would, but he is one of few who is so outspoken in his dislike of killing.
To Choji, life is always better than death. Life goes on, life can change, life can be beautiful, but death… When one gets to death, everything stops.
To Choji, death is ugliness.
Choji watches the younger children play and grow, unknowing of how utterly hideous the world can be. He fights for them, for the day when the children can grow up without having to kill.
Choji despises killing, but for those little kids on the playground, reveling in their own innocence, he is willing to tolerate ugliness for a little while longer.
After all, it's for the children.
If you're going to flame me about something, please choose something more substantial than the fact that I happen to abide by the "Haku is a girl" theory.