One of the plot bunnies that have always niggled at the back of my mind is a divergence after Harry, Quirrelmort confrontation.

Harry is an eleven year old who has just killed someone. And has been told that under certain circumstances it's ok to kill people. Sure Dumbledore used different words, but it can be easily interpreted as such.

There is much potential in a kid learning this lesson. Yet I can't really think of a story that uses it.

So are there any out there?

 

Are you looking for the story of Harry changing the attitude after Philosopher's Stone or the story about Harry using Quirrell as an example of 'I've killed before'?

 

Gloves by Myst Shadow is a one-shot that deals with the aftermath of Harry burning Quirrell to death.

Not what you're looking for, but somewhat related. No plot divergences though.

 

Not quite what you're looking for but pretty much along the same lines. A post-CoS story where Harry makes a different decision in the chamber. (And if you really wanted to, you could imagine he was influenced by Dumbledore's words after Quirrelmort's death.)

Forging the Sword by Myst Shadow:
https://www.fanfiction.net/s/3557725/1/Forging_the_Sword

 

Keep in mind that this has not be updated in a while :

Updated: Aug 20, 2014

 

It is still worth the read, even if it never updates again. In terms of characterization and growth it's one of the best in the fandom.