So Nika waits by where she expects grownups to come in, and she reads about magic on her pen.
"Ma'am. You should come home. It's Miles - he's not hurt, but - you should come home, ma'am."
This is not the explanation Miles would have produced if he'd been in charge, but it seems to be inexplicably effective.
"This way," says Nika, hopping up to her feet, falling over, getting up more carefully, and walking to where Miles and Bothari are. "And Ivan came too but he didn't bring home anything interesting, his grownup was boring and just told him not to try aged fish because he won't like it, Ivan had the most boring grownup."
"You need to let me out of this thing now, the magic blood from the magic place fixed me," insists Miles.
"I will take you to a doctor to check that in a little while," she says. "But first I want to talk to the Sergeant. It's very important."
"Fine," Miles grumbles.
"Sergeant, will you come and sit with me over here?"
Well. That's... that's something.
She reads it through. Then she looks up at Bothari.
"Did you meet... another Miles, in the 'magic place'? Did he give you this letter?"
We assume you can distribute portions of this letter to whom they may concern in some sensible manner. See also the letter Bothari was given.
"We" is two of Nika's "alts", this apparently being the term of art for versions of the same person from alternate universes; a picture of us with Nika is enclosed. Our names are Isabella T'Mir (the one with the pointy ears, from a world substantially different from your own in many ways) and Linyabel Miriat Vorkosigan (the one with the hair, from a world very like your own except in our own respective origins and quantity of hiding magic), the latter surname acquired by marriage (yes, this was very awkward to discover). If you or Nika want to find out where she came from the name regularity may provide a clue, although since we look much more like each other than like her it's possible name sound also varies, perhaps too much to be useful.
We and several other people have all accumulated in a magical interdimensional bar by a combination of coincidence and summoning our friends and family. Attached is a picture of the bar's explanation of how her door works. Being enterprising people, we have taken considerable advantage of these circumstances and sent your children and nephew home with some items.
Linyabel's universe being a few years ahead of your own and Isabella's having proceeded along a markedly different technological track, we have sent some devices of Linyabel's invention, called "pens", which should interface reasonably well with your computing technology, and have loaded them up with various useful contents, including a) how to reverse engineer the pens themselves; b) information from Isabella's universe on faster than light travel, which may or may not be physically instantiable in universes unlke hers in some way; c) textbooks originating from your own universe but apparently highly obscure to much of the population, on the subjects of magic and relatedly the presence of non-human creatures which can be disguised including from themselves as humans indefinitely.
We would prefer that Nika directly receive the profits of the development of pens, as her alt invented them. It is probably reasonable to delay consulting her on business decisions, and to keep most or all of the money in some sort of trust or just reinvest it, until she is at least six, perhaps older. (We can't be sure precisely how to expect her to develop based on ourselves, as Isabella is half-alien, which may have slowed her down, and Linyabel is haut, which certainly sped her up. Both of us think that we could have been responsible with a fortune and adult non-binding advice at or by age six.) Linyabel has a version of Gavril Tsipis and approves of him wholeheartedly; he could probably manage the enterprise to good effect with at least one technically-inclined helper and at least one offplanet distribution agent (unfortunately, Linyabel's offplanet distribution agent is likely eight years old in your world right now if she is present there at all).
Pen sales figures are attached to help with initial budgeting, and deployment order of operations. We have included plenty of spare pens for Simon to suspiciously take apart, including the versions which Linyabel's alt of him consulted on wrt cryptographic security. The children have already claimed their own pens; we have also included (labeled) copies of the models selected by Linyabel's alts of you, Aral, Simon, Alys, Gavril, and Gregor.
It seems moderately unlikely that Isabella's universe's faster than light transit mechanism ("warp drive") will work in your universe or in Linyabel's, because it is unheard of for species in Isabella's world to develop past about twenty-third century levels of technology at the latest without managing to invent it unless they also manage to extinguish much of their population somewhere along the line, become beings of pure energy and bypass the need for space travel, or repress research into relevant fields entirely. The presence of aliens in her world may be a confounding factor but were not directly involved in the drive's invention by humans on her Earth; it seems likelier that some other obstacle will interfere. Regardless, books on the subject are included. We have no strong preferences about who should benefit from the commercialization of warp if it works. Isabella did not invent it and in fact spent many years distributing it to plagiarism-inclined pre-warp scientists and mathematicians on a volunteer basis.
Our estimate of age six as a probable age of reason for Nika also holds for permitting her to perform magic unsupervised, although depending on how well she takes to the neatness required she may still benefit from help and double-checking on her diagrams. The impression we've developed from looking at the books is that knowledge of the existence of magic is effectively restricted to people who are or know about non-humans. How it has managed to remain secret for this long is unclear and we do recommend finding out before going in any way public. If you locate such a thing as a magic school we recommend allowing Nika to attend unless this is obviously unsafe for some combination of Barrayarans, dragons, Vor, girls, etc. (whether she will want to attend magic school is not in question but we cannot predict the surrounding culture except by rampant speculation).
As far as the non-human creatures go, the bar, which informed us that Nika is our alt despite her dissimilar appearance, also claims the ability to determine people's species, even thoroughly disguised, and we have no reason to disbelieve her claim. According to same, Nika is a dragon, and your Miles a unicorn, and your Ivan a firebird, and your Bothari a bugbear (diagnoses of people who were not present is unavailable). Conventional species inheritance rules found in books from your world imply that at least one biological parent of a non-human is the same sort of non-human. Since unicorns are widely understood in the non-human community to be nonexistent unless our textbooks are systematically misleading, it seems most likely that a strain of unicorns has been dormant on Barrayar since its initial colonization, or in some way arose spontaneously during the Time of Isolation, and that Miles inherited his species from Aral. Incidentally, Ivan does not seem very pleased about being a firebird. You might not want to belabor the point with him.
We have attached a list of unfortunate disasters both within the Imperium and throughout the nexus occuring in Linyabel's universe between the years 2978 and 3001 which could conceivably be averted by the placement of relatively trivial resources accessible to probable readers of this letter. While they may not all match, especially if you succeed in avoiding some of the early ones and this has knock-on effects for later items, preventing even just one would likely be worth the time it would take to try to intervene for them all.
Isabella wishes to register that she is generally prone to calling both of her parents by their first names when they are not around, and she is not adopted; therefore if you notice Nika doing this you should not assume it is because she is adopted or that she has complaints about her parenting. Linyabel has instances of both of you, albeit as in-laws, and expects Nika to have rather few complaints about her parenting.
Attached are biographies of both of us, and more pictures, including a picture of Isabella at roughly Nika's age with her parents on her father's home planet (in case there is any resemblance between her parents and Nika's birth parents which could demystify her origins; we imagine Simon is very disgruntled about her mysterious origins). These are included principally for Nika's own reference and curiosity later on but they contain nothing we are not willing to have seen by viewers of your choice, although another tidbit of peculiar alt-related coincidence of the same general flavor as Linyabel's marriage to her Miles appears in a sidenote within Isabella's biography, and you may wish to be circumspect about springing that on people. (Specifically, in 2979 in Linyabel's world, Miles was cloned - see list of unfortunate disasters for details; the clone's childhood is a tragedy and the project for which he was made a would-be catastrophe - and the bar labels Isabella's husband said clone's "half-alt" despite total lack of physical resemblance between them even to the level visible between us and Nika.)
Linyabel has also taken the liberty of supplying books in the oeuvre of Thalia Gimicar, an author whom her Cordelia favors, some of which are not likely to have been published yet (prior publications are included in case you have the misfortune of living in a universe without Thalia Gimicar).
Best wishes,
Lady haut Linyabel Miriat Vorkosigan
and Isabella T'Mir
"Ivan found it! And he got me, and I got Miles, and there were our grownups in it, and they gave us stuff and we came home from it. Look at this!" She puts her pen in drawing mode - this takes her a couple tries; it's not that accustomed to her gestures yet - and draws a squiggle through the air. "One of my grownups invented these!"
"They didn't look like me the way Miles's grownup looked like Miles and Ivan's grownup looked like him - Gregor, Ivan's grownup was so boring, it's sad - but the bar said they were my grownups, I'm going to be like them when I grow up except different looking. And a dragon. And adopted, they weren't adopted."
This calls up a tutorial! The tutorial explains that a pen is very like a comconsole. It tells him that he can change its default gestures if he wants, and explains the default gestures to a) make the pen work almost exactly like a comconsole, b) draw, c) write with gestures in Cyrillic, d) do specialized pen-things that comconsoles cannot do. He is supposed to imitate these gestures as they are introduced so the pen can learn how he holds it and moves it. It is a very good tutorial. Linyabel hires excellent help.