I'm not surprised that you are unfamiliar with her work, it is erotica so much less well known. I found this part of her uni applied well to your balrog conjectures, however. And yes, I think it would be excruciating to go through. Her Sempervians have to go through rebirth quite often, I imagine they do anything possible to avoid the experience.

At the kernel of the balrog entity must be a physical form because it is that which Gandalf battles through water and flame, and it is a body that rests on top of the peak. Perhaps in the early days of their development they might have been able to choose their form, but as they chose one form again and again, maybe they lost the ability to experience other shapes? Just a suggestion. Well...back to my research :-)

- Erulisse (one L)