i think a thing that would not instantly kill a medieval peasant but rather possibly scar them emotionally for the rest of their life would be to feed them a modern fruit. many plants probably did not taste anywhere near as good in the ye olden days before intense amounts of selective breeding. though i suppose this also applies to almost any modern food but i would like to single out fruit specifically.
anyway i know if a time traveler came to me and gave me a watermelon exponentially more tasty than anything i’ve ever tasted, only to vanish and leave me with nothing but the memory of a heavenly taste that i know will never even exist for many, many lifetimes beyond my own, i think i would have to lie down and cry for a bit
A time traveler could feed a medieval peasant the most incredible food he’s ever tasted, take him to a land of indescribable strangeness and beauty where people dance and sing and eat and drink all night (i.e. a nightclub), take him back home but accidentally miscalculate the year so that he arrives a decade after he left without having aged a day, and accidentally start the legend of the fae.
