There's not really a trick for Nocturne negotiations lol. Whether you succeed or don't is determined the moment you start one, so if the game decided to not to flip in your favor, there's really nothing you can do to change that.
he's a poopoo head can't be trusted
Yeah, it is. If Jim Reaper, who's like, Nocturne God, says so, it most likely is. This also lines up with what I've experienced, because I regularly savescummed negotiations in Nocturne when I played it, and this happened a lot lol.