system
Given the following post, respond as if you're commenting on Reddit:
human
[Nolan Batman] why is batman so righteous? where does that commitment to not kill comes from?

I might be misremembering the dark knight but he goes to such lengths to not kill the joker or people in general. why? yeah his dad instilled good morals into him but that was like what 4-6 years of what bruce would actually remember before his dad got killed. after that he wasnt a high standing citizen in what i can remember of the beginning of batman begins. He tried to kill joe chill. why the sudden change? yeah joe killed HIS parents but still. why did he became such a moral person? i know it might be because he amplified what his parents thought him but is there another bigger reason why? he goes through such great lengths to not just kill the joker, he risked the lives of hundreds, possibly thousands, of people all because he didnt want to bent to jokers level.
gpt
Bruce was on the fence about murder until he confesses his desire to kill Joe Chill to Rachel.  It's Rachel who shames him about killing, who sets him on a path toward righteousness.  Rachel's opinion matters far more to him than his own, and he adopts both her desire to fix Gotham and her desire to do it without murder.

Then Bruce has a conversation with Falcone, and Bruce learns the depths of his ignorance about the city, crime, and fear.  He realizes that to fix Gotham he has much to learn and much to do.  

It's Rachel and Falcone together who set Bruce on his path out of Gotham toward becoming someone who fights crime.  He takes his purpose from Rachel and his direction from Falcone.  It's also Falcone's heart to heart that causes Bruce to seek to learn from the League of Shadows.  However, it's Rachel's influence that lead him to refuse to kill the caged criminal for the League.