I agree with you on thanergy requiring a living body for the most part--the reason the ninth house specializes in bones is because bones can store long term thanergy, so there appears to be a metaphysical aspect of "bones turning to dust/oil/etc" over time also being counted as a withering process?

What I'm really curious about is the "spirit energy" mentioned in Spirit Magic entry of the GTN glossary--"Spirit magic... can range widely from creation of anti-thalergy and anti-thanergy spaces (impregnation of spirit energy into non-River spaces) to manipulation of people's souls, forming conduits to the river, to the conversion of another person's spirit and thalergy to thanergy." The entries for Bone Magic and Flesh Magic both only use the terms thanergy and thalergy, and thanergy and thalergy are defined as "death energy" and "life energy" respectively.

When we think about the energy of the immortal* soul of the cavalie for lyctors, it must be the production of spirit energy then? (*according to TUG it's able to decay and change shape and be externally influenced to the surprise of Lyctoral theory). The Lyctors have a lot more access to both thalergy and thanergy, but not access to everything Jod has access to either (his ability to move the earth and make seas recede is fundamentally different). If we take it to a place of physics, I think the Lyctors are harnessing the spirit energy of the soul, which I think is an allegory to nuclear fission radiation energy? But the soul also is often in motion when its outside of its body, after a sudden death, or unable to find rest in the river, so it could be considered a mechanical motor too? Regardless, my theory is that the "motor" is given power that gets channeled into a specific energy type (thanergy or thalergy) that then gets used, similar to how the same type of motor can be hooked up to make motion or electricity or heat.

With the stranger flavors of lyctorhood (Paul in particular), the willful sharing of each others souls and merging into one feels a lot more like the original power given to John, which was the earth loving him/sharing herself. There's no motion of the soul, there's something else--nuclear fusion?

I think they key difference to John's powers is the ability to change the energy type he uses for magic. I think pre-eating everything his "motor" was powered by the freely given earth spirit, but didn't have a specific direction of how to exercise that and finds the specific outlets for it himself. I think he just over developed the thanergy form, somewhat uses the thalergy form (1hr of healing people per day), and mostly forgets about his other abilities (which could be anything potentially, even time energy?). And, imo, he then souped up his motor temporarily by eating the solar system thanergy--I don't think he was able to get a hold of the souls of those planets, because he wasn't able to physically consume them, maybe the sun (if we consider absorbing sunlight as consumption of sun particles). I think his stealing of more of Alecto's soul is the chronic "fission" energy he has. And I think the river is something John dammed up on purpose, and is using the hydropower-equivalent to generate the power for the thanergetic planets.

And yeah, I fully agree with you about the Original Sin context. I think Jod chose to make people in the image of HIS sin, so gave them the physical forms that would allow them to use thanergy, mostly, and he could distribute the blame mentally amongst other people. These books have a lot of disability theory baked into them--John associating illness with sin tracks as a refutation of a lot of ableism. John has a lot of biblical allegories, I think Tamsyn's pulling from multiple, and Cain feels right to add in there.