there are really only three conflicts that come up in RPGs. Not in story, I mean between players. Usually the default mechanism for resolution is GM fiat or group consensus. I have some thoughts on that but for now, see if you can come up with a type of disagreement that can arise during play (that is about the play) that can’t be covered by these three.
Not for free
Players want the event to happen but it should require a test of skill or pay a cost.
Tone Harmonize
Something introduced is not in the perceived tone of the story for one or more players. Giving all players influence over tone can cause the tone to shift over time.
Problem Causing
A narrative causes discord with established story. Normally this is seen as a failure in the story. Can the discordant elemements become acceptable in specific circumstances?