I was reading Post-Contact Hilarity and Earth Fanfic (Post-Contact Hilarity II) and found myself coming up with various Eldrae/Human alien space bats scenarios and thought I would create a topic for them and to discuss them (Eldrae/Human alien space bats scenarios in general not just these ones) with these two to start things off
One:
Someone pokes a precursor artefact in a personal collection on Eliera which had previously been extinctively analysed (even replicated) and deemed safe (being determined to be the precursor equivalent of something like the human game Simon)
The artifact suddenly disappears in defiance of previous analysis (and unbeknownst to anybody until later reappears in an unknown cave system in Europe on Earth)
Simultaneously Earth and Eliera as well as everything within approximately two and a half light minutes of them swap places (at least in the case of Eliera the actual center point being the artifact)
Two:
A dozen a Eldrae from Eliera during the high steam age (And two dozen Bandal) are isekaied to Cambridge, England on Earth circa 1838. By 2025 the 9 of the original Eldrae who avoided being killed (1 by assassination, 1 by accident and 1 by misadventure) weld substantial economic and political power, earth is significantly more technologically advanced in some areas (the IT revolution having started more than a hundred years earlier than it otherwise would have), Most governments in developed nations have a far more hands-off approach (although not as hands off as most Eldrae would prefer) and The population of Bandal/Dog crossbreeds is thriving (unfortunately still not quite as intelligent as the initial Bandal population although this is being worked on)