When Not To Kill

There are times when a character could have been killed but wasn't and we think about what might have happened if he had been. In The Broken Sword, XIX, Skafolc could have killed Valgard in his sleep but it:

"...would too likely make a noise and thus cost him the sword." (p. 130)

"Castelar wasted no time finishing [Varagan]."

-Poul Anderson, "The Day of the Ransom" IN Anderson, Time Patrol (Riverdale, NY, December 2010), pp. 641-735 AT 15 April 1610, p. 666.

Manse Everard has "already" met Varagan "later" so, although the latter could have been killed at Machu Picchu in 1610, we already know that he wasn't.

Lisbeth Salander:

"...opened the pistol and checked that she had one round left. and considered shooting Zalachenko in the skull. Then she remembered that Niedermann was still there, out in the dark, and she had better save it."

-Stieg Larsson, The Girl Who Played With Fire (London, 2009), CHAPTER 32, p. 562. 

So Zala survives into Volume III but Lisbeth does not wind up with a charge for murdering him.

You can probably think of other examples.