When the series ended I remember reading a long Shawn Ryan interview, (or it may have been more recent), but he said that Dutch cat scene wasn't as crazy as it seemed, something like the stress of the job, and it being an isolated incident. And that Dutch was so disturbed by it, he didn't enjoy it, or feel nothing, which showed he wasn't a sociopath. But, maybe Sutter and Ryan had differing opinions, there.
One of my favorite shows of all time, own every season, Vic was kinda a broken man by the end, but he still went out with a smirk and a pistol. He seemed impacted by the changes, but still didn't give a fukk. Vic Mackey is second only to Tony Soprano in the one liners category. He was routinely ethering Shane, esp.