On Primal Summoning

[Miyha]

Which now begs a curious question:
Is Y'shtola a primal?

It is possible to reduce yourself to aether and travel the lifestream, that much we know - Teleport, Flow, Return etc. But how are we put back together and what are we made off afterwards? Something that, apparently, can be made to and from aether, because that's what we dissolved into to travel the lifestream. Aren't we then technically made off aether? And if so, why wouldn't we all need aether for sustenance, too?

Could A-Towa-Cant and Severains girlfriend linger indefinitely if they just consumed more aether for sustenance? And why did they not have to do that during their lifetime? Is the difference maybe just a physical vessel? But why do Shiva and Thordan drain aether too then?

What of Carbuncles, Fairies etc? Those seem to be harmless, but are clearly aetheric beings as well.

I feel it's a little less clear cut than it seems to be.

Y'shtola is using her own aether to be able to see by sensing the aether around her. She's technically draining her own life force, not that of her surroundings as primals do. Matoya warned her that doing this was shortening her own life as a result.

Fairies/carbuncles/egis use the summoner's aether to manifest as well. That begs the question though, how that doesn't too drain the life of the summoner... Unless the effect is too minimal, or the summoner simply replenishes that aether.

Which leads to the question of all living things draining aether. My understanding is that the difference between primals and other life is that primals are like black holes: the aether they use up simply disappears/ceases to exist. Like how the Void is essentially an aetheric vacuum. Other life simply recycles it; though in Y'shtola's case, perhaps she is using her aether faster than it can be replenished by that around her?

EDIT: At the Shiva and Thordan thing, the summoners (in these cases Ysayle and Archibishop Thordan VII) draw the aether from around them to transform themselves into primals. In doing this they still drain and permanently consume the aether around them, because they're still primals, and that's just what primals do. :P As to why people can't linger indefinitely, perhaps it has to do with the fact that in order to permanently manifest after they have lost their physical form, they NEED to drain aether in this way... They can temporarily manifest, but with no physical anchor of their own, the aether just returns to the lifestream. Primals never had a physical form to begin with, so giving them form requires a massive amount of aether (crystals) PLUS an even bigger amount over time to remain manifested.