WARNING: This is 12&13 stuff. If you havn't seen them, you might not want to
read.

Kagato discovered that Tenchi can't be copied.
Zero and Dr. Clay discovered that Ryoko can't be copied.

Why? In Ryoko's case, because of the jewels.

I was shocked, on careful re-viewing, to discover just how vague Washu( and
the editors) keep things about the jewels, there may be a big surprise in
store. However, the conclusion that Zero was subverted by Ryoko's defensive
double because of having to take the jewels seems clear. What is not clear
is what lever Washu used to extort Ryoko into taking back the embarrassing
double. I think the idea that she had too to get the jewels back is a good
subconscious patch on my part.

It becomes clear when you consider the mental links Washu has told
Ryoko(unlikely to be lies) that the jewels create, that the jewels are
inextricably part of Ryoko, and that the mental links are the real source of
Washu's information once she realizes that Zero Ryoko has been substituted.
(interesting that Washu doesn't normally spy on Ryoko's mind).

Might have beens:  It is noteworthy that Dr. Clay would have been in big
trouble anyway, had Zero not found it necessary to take the jewels. He would
have had one irate Oni in his fishtank, able to create lighthawk wings, and
powerful enough to collapse a black hole, undoing its' effects.
Likewise, had Kagato succeeded in killing Ryoko, he would have had dead
jewels, and one mad as hell higher-dimension-tree/goddess inside his
defenses, with no power to control her. Since Tsunami and her trees were
willing to risk Ryu-oh, Aeka, Tenchi, and Ryoko, all to kill Kagato,
suddenly her seeming surrender to insert Tenchi makes sense.

After all these sensible(to me) comments, let me indulge one wild eyed
speculation. What the three sisters may be up to in the Tenchi Muyo
universe(regardless of whether I am right about what three sisters they
are), is a little god-making. Maybe they are trying to come up with a
universe where the gods are decent people rather than the usual megalomanic
swine.

BTW: I read someone's comment that the logic I suggested of Sasami being
Tsunami's avatar-to-be might imply that Ryoko would be Washu's avatar to be.
A tree is an akward avatar for a god to humans, but Washu seems quite happy
with her current incarnation. On the other hand, Washu really blew it with
that entertaining stunt of turning mature in OVA 8. Nothing spooks Tenchi in
these space girls quite like sudden changes. For all her faults, such as
blowing holes in the ceiling, Ryoko is very much a what you see is what you
get sort of gal.

                                Greg

*A foolish consistancy is the hobgoblin of little minds, adored by little
statesmen and philosophers and divines. -Emerson*