I decided it was time to reread all the Vimes ones earlier this year. I think I always knew he was the hero of Men At Arms, but I hadn't noticed either how much he was the hero of Guards! Guards! (In my defence, I did first read it at 15 and, like you, familiar with fantasy tropes but not police procedural ones).

Someone said once they could see how the Vimesy of Night Watch had developed into Commander Vimes, but not the Vimes we first meet. I can - and that's almost the darkest part of the whole series, for me. Except that he grows out of it again, given the hint of a chance to grab.