It’s right that in the Dramatica Table of Story Elements, an MC throughline in Universe or Physics will be a do-er,or in Phsychology or Mind will be a be-er. But my understanding is that that comes solely from the quads designation as internal or external and not from the horizontal relationship with the other quads. An MC with a Universe throughline is a do-er regardless of where the OS lands.
But start and stop, I’m sure you know, do have a relationship like that. When the MC and OS are horizontal, it’s a stop story and when vertical, a start.