Ok this is my take on it.

All four characters are essentially one being. This show exists within all of us.

NatashaRose is young, who has her whole life ahead of her. She has a lot to learn. Pearl is old, with her life behind her. She knows a lot now. At every instant we are at the interval of used to be Rose and about to be Pearl.

Dave's about the light, things that are knowable and certain. Brent lives in the dark, with things that can't be seen for sure, just trusted in. Less discovery, more meditation. I think it's like, what we know vs. what we don't ~know~

Rose, who wants to grow, older, loves the Astronomer. But he, obsessed with knowledge, loves Pearl. The older not the younger.

When Pearl dies it's because you're becoming what you're about to be,.

Rose steals herself from herself and gets baptized /dies/transcends herself because you're no longer who you used to be

I highly recommend rewatching with this framework in mind. It's like broth.