Conversation Casualty

""I offer this advice to you two: If you're going to destroy something... do it mid-dialogue. They always expect you to finish talking first.""

- Dark Pegasus, DMFA vol 923

Bob and Alice are having a fairly mundane conversation. Bob stares absentmindedly out the window, and Alice is walking around the room behind him. Without changing the tone of her voice or the subject of the conversation, Alice picks up a gun, walks up to Bob and shoots him.

This trope could be used for several reasons. To spice up a boring conversation, to establish a creepily detached mood, to reveal a traitor, to portray a character as deranged, overly methodical, a dog-kicker, or to show they long since crossed the Moral Event Horizon. Bonus Points if the victim is Killed Mid-Sentence.

Sister Trope to Talk to the Fist, where the attack isn't necessarily lethal and the talking is related to the fight. Compare Have You Told Anyone Else?. Not to be confused with Talking the Monster to Death or Logic Bomb.

Anime and Manga

 * Seishirou in Tokyo Babylon and then in X 1999. Or, second thought, the whole cast of X. They fight while exchanging pleasantries all the time. Seishirou is especially bad, though. See the end of Tokyo Babylon. He'd kill someone while wondering aloud about tomorrow's weather or something. Or how cigarette can kill you. (he did this)

Film
"Jules: Oh, I'm sorry. Did I break your concentration?"
 * The Matrix. Cypher is brought back to the Nebuchadnezzar, talks to Tank for a while and then shoots him in the back with a Lightning Gun.
 * In L.A. Confidential, Dudley Smith shoots Jack Vincennes mid-conversation without so much as a word of warning.
 * There Will Be Blood. Daniel Plainview wakes up the man who claims to be his brother, and forces him at gunpoint to say who he really is. During the mans confession, Daniel puts away the gun. When the man is done explaining himself, however, Daniel unexpectedly draws the gun again and kills him.
 * Terminator 2: the T-1000, disguised as John's foster mother, is talking to him on the phone, when the foster father interrupts her about their madly barking dog in the backyard. It promptly skewers him through the mouth with its morphing swordlike arm.
 * Francis Walsingham in Elizabeth pulls a reversal of this on a young man guarding him after a few philosophical words on the ugliness of the world. Walsingham is philosophizing while looking out the window when the young man pulls a knife on him. He then calmly talks the man out of stabbing him, gets him to look out the window himself, then calmly slits his throat without changing the tone of his voice.
 * In Pulp Fiction, while Justin Whaley's character is trying to explain away the action's of him and his cohorts, Jules casually walks up to one of the cohorts and shoots him.


 * In True Lies, Harry Tasker test drives a used car with the lot owner, Simon. Harry gets Simon talking about the woman he seeing (Simon doesn't know the woman he's seeing is this guy's wife) and then kills him with one well-placed backhand. A moment later, we see it was in an Indulgent Fantasy Segue.

Literature

 * American Psycho - Patrick Bateman certainly contemplates taking a cordless drill to the head of a lady he's chatting up.
 * Also Played With in the movie when Bateman continues talking to his drunk/drugged soon-to-be-victim about retro music while putting newspapers around him, putting on a raincoat, and finally killing him with a huge fire axe.
 * This happens in the end of Of Mice and Men. George is calmly talking to Lenny about the farm they've always dreamed of; he asks Lenny to close his eyes while talking, and George pulls out a gun and shoots him in the head. A non-villainous version, as George is doing this so that Lenny will die calm and happy.
 * In The Big Sleep, Philip Marlowe overhears a conversation with Harry Jones, an informant, and a gangster named Canino. Canino makes sure Harry has a good stiff drink-- which is poisoned.

Live Action TV

 * The pilot episode of The Sopranos had one of these. Christopher Soprano shoots Emil Kolar in the back of the head after a while of polite discussion.
 * A sympathetic variant in The Vampire Diaries - Rose is already dying, having been bitten by a werewolf; Damon gives her a Dying Dream of her human life centuries ago, during which he challenges her to a race. He stakes her during the countdown.

Theatre

 * In Pippin, Pippin, disguised as a monk, kills his father Charles at the end of a conversation about the meaning of empire.

Video Games

 * Mass Effect -- This is how the conversation between Nihlus and Saren goes.
 * It is possible to end one subquest in Mass Effect 2 by talking to a mechanic repairing a plot-important weapon, asking him about what is going on and then ending the chat by stabbing one of his electric tools into his back.
 * In Nimdok's scenario in the videogame adaptation of I Have No Mouth, and I Must Scream,.
 * In the NES game Day Dreamin' Davey, many knights in the Medieval stages can talk in Ye Olde Butcherede Englishe and give out info before Davey can kill them.

Web Comics

 * In DMFA, during a flashback to the first meeting between Dan and Dark Pegasus, DP kills a girl with a blast of magic in mid-sentence. See page quote.