My first play through I chose a low chaos mostly non-lethal approach. Partially because of the game tip which said bodycount affects the ending, but also for role-play reasons (how can I prove my innocence if I kill a bunch of innocent guardsmen?)

I had a good ending, Emily was a sweetheart, Empire entered a Golden Age.

So for my second playthrough I decided on a bitter angry and vengeful Corvo, who carves his way to his targets with blood and hellfire. An upside to this playthrough is I have done a lot more exploring and found more side areas since I am less worriede about being detected this time around. I mostly don't even try to be stealthy. No tact, no grace, no subtlety, no mercy. Just killing any non-civilian I see plus a bunch of weepers.

I hadn't really noticed ANY dialogue or attitude changes in the NPCs from my first (delicate stealthy and careful) playthrough... until I assaulted the Lord Regent's safe room in all my bloody glory and killed him.

All of a sudden, Samuel hates me and says he shouldn't be helping me because of all the killing I've done (yet he is anyway, despite hating me... I don't get that) when he had all the same cordial and amicable dialogue on the boat drop-ofs and pick-ups he did in my low-chaos playthrough.

Basically, Samuel treats me completely the same as far as I can tell in low and high chaos... until I kill the Regent, then he hates me out of seemingly nwhere. So, when exactly does he start hating you?