First of all, I want to tell you that the core of a drama, that is, the most important thing in a script, is to have contradictions and conflicts. This contradiction is not what we call fighting and quarreling in real life. You got it? What we are talking about is whether there is a play, that is, whether there are contradictions or conflicts, or whether there are knots that cannot be solved. As a screenwriter, you should set such a knot and try to untie it.
Looking at the conditions you gave me, I think, first, you should let your characters meet, that is, set a scene and let them live in this scene.
Second, set an event to pester your characters.