"Humans are lower-maintenance but if you have a particularly tractable Elf available the osanwë benefit may outweigh that."

"I expect to eventually have sufficiently tractable Elves available but am uncertain if I'll have them in a few days. I'll send you the best option available in forty-eight hours."

"Thank you. My lieutenant could also use a replacement in a similar time frame but is more likely to be convincing with the being impressed and tolerant of the occasional singing and such."

Nod. "If I find you an Elf who'll do it for a decade, are either of you likely to get attached and disinclined to move on in a decade?"

"We're neither of us the type; some of the lower ranks might be susceptible."

Nod. 

And he considers for a while and calls someone into his office and tells them that he's been hiding from his people for a long time the activities of the interdimensional collective which has been wavering on whether to oust and execute him, and that Independence is now safely out from under them by coalition with another people subjected to the same treatment, a people who innately have no senses and cannot see or sing or experience the beauty of the world without taking a host. And it is in the interests of this kingdom to help the Yeerks in this brief time before they are independent through the use of daeva, and to help them especially by lending eyes and hands and expertise, and is he willing to give the budding alliance a decade's service as a Yeerk's companion? 

It does not take forty-eight hours to find two convinced Elves. He teleports them over to Issiak.

And Ehtelion and Yomenië can be carefully exited and stunned while it's assessed if the new hosts are sufficient to allow the Space Elves to be put out of their misery.

Issiak's new host is nervous, but he served on the front lines of the war against Melkor, facing a fate infinitely worse than death, for King and country, and he keeps reminding himself of this, and he is certainly regarding himself as a volunteer for an onerous duty and not as a prisoner. He promised the King a decade's service and he can do that, assuming they go pretty places and sing occasionally.

Yes, yes, osanwë will save enough time to be worth it. (Issiak does not put it in these terms to his host.)

The Yeerks get to work building a Kandrona generator; they don't have an infinite supply of the vegetative substitute and it would be nice not to cut it too close waiting on the demons.

Independence throws a festival. Elves are actually more willing than humans to be hosts, both because they're more obedient to their King and because they can keep talking to their friends and working on their projects. Someone determines that you can even enchant metal while a host and at that point there's a great deal of demand for Yeerks, assuming said Yeerks are willing to keep to-be-enchanted rings on their fingers, so the inventors can focus on their enchanting and not worry about sustenance and maintenance of their house and home. Elves are mostly interested in decade-long contracts; the interested humans are mostly not willing to commit that much time. 

It does not inconvenience Yeerks at all to have rings on their hosts being enchanted and do the host maintenance they'd have to do anyway.

Midnight writes the peal. Letter to Cam: there's a recording of me swearing to the truth of the contents of this letter. We have no designs on you and yours. We would simply like to live independently of you. If you escalate our peaceful departure from your realm into a war, that war would harm many innocents; if you do not do that, we have no intention of disrupting your governance of people who want to live under you. 

And he finds a audio recorder in the lightleaper and swears to the contents of the letter. 

There's no response, but then, there wouldn't be.

There is a lack of an invading army, but that might mean the peal is trying as hard as they can and just hasn't found them yet. Once the daeva Yeerks are grown they'll be able to check. 

That's a ways off. (They could kill off the daeva Yeerks now, but Issiak prefers to have some opportunity to evaluate their personalities before granting them magic powers and indestructibility.)

What a reasonable preference. Issiak has osanwë and can get a great deal of insight into their personalities.

It's very handy, osanwë.

Independence would love some Yeerk help getting modern technology.

Yeerks can totally do that, although z-space transit won't work here.

That's okay, they're happy just to be getting computers and non-magic heavier-than-air flight.

Those are all totally doable. It'll be easier when the demon Yeerks are grown and dead and summoned.

To Elves that seems a short time away.

They move the lightleaper out of the buffer dimension in case Joy can target for a lightleaper. They can teleport with it when it's necessary to interact with the multiverse, which it isn't, desperately curious though Midnight is.

Two strangers appear in an empty field near a Yeerk pool. Humans, tall ones, a man and a woman, holding hands, both wearing obviously-magical glowing pendants. He's got a coily green thing like a very abstract snake, that tells onlookers about his warm heart and cynical, fatalistic sense of humour; she's got a ripply orange-pink rectangle that tells onlookers about her insatiable curiosity.

People are not supposed to suddenly appear near Yeerk pools, especially not with strange magical powers. They are promptly stunned. It's mildly surprising when that works. In go some Yeerks.

When the strangers wake up, they are confused and alarmed!

Their names are Sehana Irtezi Daeredh and Oravith-kelinre Aliharno Tyela. They are from a world called Nuime, which has never heard of the peal, although it's heard of an Arda. They are dimensional scouts. Sehana Daeredh - 'sehana' means refuge or sanctuary - was supposed to keep his wife safe from assorted strange hazards while she hopped them from world to world looking for interesting new places. He has no idea how the stun got past his defenses. He's pretty sure the world is doomed. Tyela, meanwhile, is too panicked to even think about that.