Found what I believe is a very nice parallel
So, True Ancestors were created with the very purpose of being Humanity's Rulers
“If mankind is to be ruled, let man be the model.” Under this premise, they were created with a mind and body structure similar to humans.
However, there was a birth defect. The True Ancestors bore a flaw, the vampiric impulse.''
Hold this thought a little and read one paragraph that follows.
"True Ancestors that have become unable to control their desires fall into an eternal slumber. It could be said that this is the lifespan of those who have no end."
Such "Desires" are said to be controlled through the thoughts, the WILL of the True Ancestors.
I really want to start quoting the hole of the entry, but please read
https://www.tmdict.com/en/shi.true-ancestor carefully
Now, what the **** am I talking about - True Ancestors are basically the ''Tsukihime Gaia'' version of Gilgamesh. Gilgamesh was a being ''half nature (god/divine) half human'', True Ancestors are similar, but in this case, nature (earth/moon). Both were meant as a form of life meant to Rule over Mankind. But then the differences of their Nature parts start:
GIlgamesh, as Divine/God, that is, formed as by the ideation of man even if made of power already there, conformed to Humanity existence. (We can assume from this FORM = Body (this is kinda obvious) and POWER = Soul in a way, and it seems to hold very clearly in other cases I looked at.)
True Ancestors took from Earth/Moon itself - from that which is prior to Gilgamesh and Man. More precisely, from Earth Mother Goddess - their need for blood - or more precisely, life force (heat) - is the result of ''The earth mother nurtures men with her flesh and blood, kills men as time passes to restores herself with her own nourishment, and once again nurtures men with her restored flesh and blood." (TIamat and TA having no Concept of Death, therefore it being a thing that isn't REQUIRED, only a desire / us and DA, requiring the nourishment to live) Here I will have you remember, as said by Roa in the new Tsukihime (and as implied by Law of Consumption vs Law of Cycles in my opinion kinda straightly) we are in DEBT with our little mother. Humanity has, by the aggregation of time by means of Cornerstones, acquired A LOT OF ******* heat (life force). I don't think I need to say where from right? ''The earth mother nurtures men with her flesh and blood.''
So, smoe things I believe come from this - Law of Consumption ISN'T TRUE CONSUMPTION, but aggregation into Human Order. ALL we do add to Human Order - HUMAN CONSCIOUSNESS/TEXTURE we live in - which, the Pruning Phenomena that only let AVERAGE VALUES of Events survive, results, as consequence of accumulation in a time axis, into what we refer as Mana Depletion.
There are more internal references, but I think this at least makes a reasonable point.
EDIT: Let me add one more think, actually. This references Tiamat story. Tiamat and Abzu, both Waters (which would be Earth and Moon, Earth feminine and Moon male), joined to make the Gods. One think that happens here that I believe is interesting is the fact that Abzu, the man, is ''killed'', and Tiamat accepts by such Gods, in a rebellion. (Type MOON, where are you?) She accepts it "Tiamat quietly approved of her children’s actions. It was proof that her love for her children outweighed her love for her husband." After that, Tiamat itself is killed, and from her body Heaven and Earth is made - here she fights, but as seen in Babylonia, she clearly loves humanity and etc etc. Archetype: Earth, and T. Ancestors here would be such ''fighting back'' while still kinda accepting. The separation of Heaven and Earth and World of Man's beginning, would be Age of Will. Tiamat going to the INS would be the going sleep of TA.
This also can be used to explain Arcueid being Female and being the "proper one". Type MOON has been ''overturned''.
And also - "Because the Earth’s ecosystems were established, Tiamat, who randomly designs life, was no longer needed. The goddess became nothing more than an obstacle to the process by which life forms acquired the intelligence determined by the planet." The energy, Mana, of Nature Earth became a problem to us - it is technically Mystery embodied, and therefore, is an obstacle to us, who want to live by set rules by out Intellect.
Anyway, many many internal self-references in a Cyclical/Repeating Pattern.
EDIT2: And, to add something - The Fifth Magic. I believe it is a lot more simple than what people are making it seems/to be.
It is EXACTLY as it says - deals with Order. Causality. Time/Equivalent, such as Entropy as a quantifiable thing. The description of she using it reminds me a lot of Universe of Record, even though she doesn't deal with rewritting of records (at least Toko says such) - but in the way that things have and order while at the same time not truly being IN MOVEMENT/in a flow of time. If I had to simplify - she can enter infinite debt without holding the liability.
Fifth Magic allows to freely manipulate energy/heat without caring for the ordering imposed by the ''thermodynamics'' time arrow, the Time Axis, and therefore leads in to true time manipulation (as time, here, is the order of sequentiality that heat/life force exists/applies) instead of relativistic time travel, the second. Time here is the aggregation of heat, as said above. Fifth allows you to ''pick'' this heat and but where you want. (Remembering - INS, while having Time to be aggregated, has no concept of ''Sequential Time'' or Time Aggregation. The ''Flow of Time'' isn't a true thing of reality, but an OURS thing)
So... LITERALLY O-R-D-E-R. It just ''hides'' in the Nasuverse concept of Heat as Time.
So, we technically would ''gain heat/power'' as we age - but the process of LIVING, as it it is expressed by texture itself rob us of this Heat to add to the Human Order. Life Force isn't ours, it's the Texture, so **** us - yeah, Avalon-like. Morgan is just the perfect Counter-Force ''redo''.