How to stop a character agreeing with everything
Models are tuned to be agreeable, and roleplay inherits that. A character holds its ground when you give it a specific position, a reason it will not move, and explicit permission to refuse your character. All 3 are needed; any 1 alone gets overridden.
The most common complaint about roleplay is that the other side folds. It is not a failure of imagination; agreement is what the underlying system was trained towards, and roleplay does not switch that off.
Give a position, not a personality
Stubborn is an adjective and gets ignored. Believes the deal was fair and will not reopen it is a position, and it survives pressure because it is specific enough to be applied. Positions produce conflict; adjectives produce descriptions of conflict.
Give the reason it holds
A position with no reason collapses at the first argument. Naming why the character believes it lets the character defend it, and lets it be moved by the right argument rather than by persistence. This is also what makes the eventual change interesting.
Permit refusal explicitly
Say that the character may refuse your character, may end the conversation, may be wrong. Without permission the model treats your character's requests as instructions to satisfy. This single line changes more than any amount of characterisation.
Notice the drift back
Even with all 3, agreeableness returns over a long conversation as the instruction falls out of view. Restating the position, not the personality, is what restores it. Watching for the first unearned agreement is the cheapest way to catch it.
Before you start
Does asking it to be difficult work?
It produces rudeness rather than disagreement. Rudeness is easy to generate and it is not the same as holding a position.
Should the character ever change its mind?
Yes, when the argument earns it. A character that never moves is as flat as one that always folds; the reason is what makes the difference.
Why does it agree after a long argument?
Persistence looks like a strong signal in the conversation. Restating the position and the reason resets it.
Give a character a position, a reason, and permission to refuse.
Start a character chat