I have the wildest theory--actually 2--about what is going on in Tsubasa RESERoir CHRoNiCLE and since it is making my mind feel like it is exploding, I have to get it out, if only so I stop thinking about it all the time.
I've been trying to think about what the whole point of Tsubasa is. I recently started re-reading through my delrey books and I stopped on the very first pages in Volume 1--the weird capsule-thing Sakura and Syaoran were trapped in, each on a different side. Insane Idea I: It made me think of a battery for some reason and that really got me thinking:
Q1: What does Fei Wang want?
A1: That answer is easy enough because he has stated his intentions very clearly on this manner (at least to us third-party observers he has)--he wants whatever power the ruins in Clow country contain. The same ruins that seem to want to 'fly' out of the desert, but, for some strange reason, something seems to be holding it back, anchoring it in the desert.
So that takes us to question 2:
Q2: Why not just take the ruins? by force if necessary?
A2: This answer, again, seems very evident and yet brings up numerous other questions--something is keeping the ruins in place, anchoring it into the ground in Clow country, despite its desperate need to escape. And this anchor is stronger than Fei Wang's capabilities. Also, there is nothing to say that the power in the ruins can be accessed if it is forcibly removed from Clow country, or even if it removed at all.
Also, the power in the ruins seems to be dormant, meaning that something is needed to activate the powers--either unseal them or turn them on. This is the point where I started smoking the crack--well, I'll get to that in just a bit.
Q3: If Fei Wang wasn't trying to take the ruins, then why did he send his solders to Clow?
A3: The attackers that Fei Wang sent weren't there to take the ruins, they were there to distract everyone, especially the King, from what was happening in the ruins with the Princess. Which is probably a good idea if you are going to try something funky with the King's little sister, who the said King is extremely protective over.
So here is the big questions:
Q4: What does Sakura have to do with the ruins?
Because it seems that accessing the power in the ruins is dependant on the recovery of Sakura's feathers, and, if this is true,
Q5: Why were Sakura's feathers scattered in the first place? if they needed to be recovered to do whatever it is that Fei Wang wants to do.
A5: Obvious answer again--scattering the feathers was not done intentionally. And this answer leads back into Q4 in that, if the feathers weren't meant to be scattered as they were, then just what was supposed to happen?
Here is my crack-ified answer:
A4: Sakura, with all her power, needs to be a part of the ruins for them to work the way Fei Wang wants them to. Remember, in the beginning, in the bowels of the ruins, Sakura was literally being absorbed by the ruins when Syaoran interrupted the process. And it was this interruption that was what scattered Sackura's feathers because, evidently for the process of activating the ruins, Sakura's power must be in its physical manifestation--her wings.
So, in my insane mind, this all started when Fei Wang was trying to use Sakura to activate the ruins in Clow country. Syaoran interrupted the process and that jarring motion was what scattered all of Sakura's fathers. See, Fei Wang was a little hopeful that it wouldn't be interrupted (this time, almost like this is his second time going through this whole scenario--and that is a totally different topic which I won't even touch right now) but was also ready for the long process of recovering the feathers world by world.
I think that Sakura is literally the 'Key' to the ruins; that Sakura, with all her power--all her feathers, needs to become a part of the ruins before they can ever work, or at least work the way Fei Wang thinks they will work.
Sakura is needed for one or more of the following reasons:
1) To break the seal on the power of the Clow ruins so that its power can be accessed;
2) To break the seal on the anchor so that the ruins can fly free of the desert like it seems to want to;
3) To 'start' the power of the ruins, like a spark or catalyst, which then can be removed after the magic is activated;
4) To act as the 'battery' for the ruins--that the power of the ruins will literally run off the power of Sakura's magic.
Number 4 is the crazy idea that came to me when I was looking at the capsule, but then I thought: why is Syaoran in the capsule too, if Sakura is the power source?
Well, Syaoran has magic too--which could also be used as a battery--the original does, and it is arguably a different kind of magic than Sakura's, even if they are both descendants of Clow here. So, since Syaoran is meant to be with Sakura (cosmically hitsuzen and all), it makes sense that his magic compliments her magic--each a half-piece of a puzzle that, when put together, make one whole.
Another way to put it is they, together, form a perfect circle, a perpetual cycle going around the circle like a closed circuit, which would make the two of them together, if manipulated correctly, be a limitless power source--each half of a battery, that, when combined and then plugged into the correct device, would give the wielder to power to change the fabric of reality or, at least, the power to cross dimensions at will.
That putting Sakura and Syaoran in that tube makes them a perfect magical battery and when plugged into the ruins, it will give limitless and endless supply of power to the ruins, which would basically magnify the power of the ruins. So, if the ruins by themselves had power to take one person to one dimensions, with the battery, it could take limitless people to limitless number of dimensions.
And, I'm even more insane here, but the ruins--they want to fly out of the sand, right?--that the ruins are literally the transportation device to take people between dimensions--the entire ruins would go from world to world, similar to the way that Mokona takes the group from world to world, but much larger and much greater control. And there seems to be plenty of room in the ruins to hold an army, because that is the current problem--only being able to transport one or two people across one dimension, and that can only be done once in a lifetime.
A small amount of people seems to be able to go from dimension to dimension, but each time it takes enormous amounts of energy and they don't always seem to have much control on where they go. The only place they seem to be able to go at will is to Yuuko's shop and that is due to Yuuko's magic purposely directing people to her shop, not their magic.
(Yuuko has mentioned before in xxxHOLic that her shop is there and yet it is not there, that it is literally in a separate dimension than the surrounding space, and that the magic spell on this dimension only allows those meant to enter to actually enter. It also seems to be Yuuko's own separate pocket-reality that she created specifically for her shop and this reality has something like a magical homing beacon--or a gravity well of a black hole--that draws travelers from others dimensions to her, so that they end of in her shop and not in a random world.)
But if the ruins are all Fei Wang wants, then he'll be able to pick the dimension he wants to go to and also bring an army with him--not good for the rest of the universe.
Insane Idea II:
The other insanity that I am entertaining is that, when Sakura and Syaoran jumped into the floor of the ruins, they never left. The ruins, which in this case I am assuming is sentient, took both of them and put them into that glass-pod device they are in at the beginning and it is now testing them, putting them through all this--the feathers being scattered and traveling between dimensions, to determine if they are worthy to wield the power of the ruins.
This idea came to me because of all the talk about how "the dream must end" and I thought that maybe the dream they are talking about is the 'dream' that the ruins have created to test Sakura and Syaoran--because, if the 'dream' continues as it does, Fei Wang may gain control of the ruins through Syaoran. And I'm stopping right here because this is way too much right now--my brain is mush after my first insane theory.