#this is a lot of complicated thought distilled down to bite-sized pieces but i think the general idea is in there

[captainsupernoodle]

I'm having a massive range of feelings about this quote specifically and the general concept of vimes being absolutely full of rage in general including but not limited to: how choice has a tangible impact on the reality of the world in Discworld (the alternate reality seen by the imp in Jingo, literally all of Night Watch), how Sam has been told that eugenics (I'M GOING TO SAY THIS AGAIN: EUGENICS, WHICH IS BAD, WRONG, AND INCREDIBLY DANGEROUS) say he has "the eyes of a mass murderer" and Ahmed told him he wasn't a killer and how Vimes realizes when he thinks he's killed the werewolf in the river that he's never actually, on purpose, killed anybody -- but how in Discworld there's a difference between being a killer and killing people and Sam isn't a natural killer but he is completely capable and even likely to kill people when he "unwinds all at once" EXCEPT that the people around him are people that HE'S taught SHOULD NOT kill step in when he's going to break his own rules (the Watchmen watch each other) and how who Sam Vimes is as a person is because of the choices he makes and sometimes those choices are reinforced by the people around him which makes the identity of Sam Vimes something that is shaped by his community

VIMES makes the choice to be the kind of person he is. the people around him know what choices he makes, and when he runs up against the wall of his own temperament they can step in and say "no" for him, and so Sam Vimes remains the person he chooses to be for another day.