The music analogy is very pleasant. Let me share another stab with similar inspiration. The parallel I'd make is with harmony. For instance in LOTR Dominant is when Frodo and Gollum struggle at the cliff of Mount Doom, they lose control of the Ring that makes an upwards arc spinning. Max tension. Fast forward, Frodo returns to Shire, music is at home again. Tension resolves. (Tonic). So setup, conflict, resolution would be pre-dominant, dominant and tonic. Subplots are secondary dominants.