A conflict can be rooted in the main plot, it can be rooted in a relationship between characters, or it can be both. Here are a few strategies for creating a new conflict in a scene.
One of the most basic forms of engagement is curiosity, what’s going to happen next? Surprises, judiciously used, can keep a story interesting, and prompt audiences to reconsider what they’ve previously read or thought. A surprise can either be a surprise for both audience & character(s), or a surprise for the audience alone.