The Protocol Droid was pretty much HK-47…how does that not fit the dark tone?
I’d say he was more like C3P0 except programmed to torture people. He still asked all of the same types of questions as 3P0 would and really behaved like him except for the fact that he was used for evil instead.
From my point of view that makes it a bit darker. That someone like C-3P0 with a few tweaks can be programmed to torture sentients and actually enjoy it. Not only that the droid has stated he killed his previous masters. As far as characters go this is the closest thing we’ll probably get to a serial killer (or someone with serial killeresque tendencies) outside of the Darth Plagueis novel.