Now posted as July's
Tome of Eldritch Omake entry! Man, for a slightly-over-700-word story, there were a
lot of typos in there!?
Incidentally, Sora, the reason to use a phoenix is partly from speed (magical bird flying faster), the need for the familiar in question to be both summonable (and hence controllable over a functionally infinite time period...though some kind of "animal control" glamour magic might be workable, it's an open question of whether it would work for the time periods and distances needed) and of animal intelligence (...can you see a fairy playing messenger over hundreds of miles when you can barely get them to stay in one place on a single battlefield?), and as yui pointed out, hard to kill (which, ultimately, is the problem with carrier pigeons, not that I'm sure that
GrimGrimoire's setting even has carrier pigeons) and intercept the message. Now if only they could work out the details...
(...which actually shouldn't be that tough; if Lillet can work out wards that keep her daughter's barghest from accidentally burning down the house, fireproofing a message container should be workable, so long as the ward doesn't just prevent the container from igniting but also stops it from transferring the heat to the message inside.)