mithriltabby | Escaped gaming meme: Fortean Twins (Reply)

Everyone is familiar with the usual sorts of twins: fraternal and identical. Conjoined twins are also well known from circuses and other catalogues of human oddities: a rare case of craniopagus parasiticus recently made the news. (The X-Files episode Humbug features a very exotic sort of conjoined twin.)

A more obscure sort is the “fetus in fetu” or “inclusion twin”, where one twin winds up enclosing the other. (This is not the same as a dermoid cyst, but they can be mistaken for each other.) Some of those live as stunted beings, while others wind up encysted, much resembling a teratoma. They tend to show up in the lower abdomen, and can go undetected there for decades, then turn out to need to be surgically removed. (With modern ultrasound, it’s much more rare for them to go undetected.) In a magical world, this could lead to interesting possibilities: a child growing up with an “imaginary sibling” who happens to be quite real could have the potential to be a powerful shaman. (A spirit might still hang around an encysted twin, even if metabolic function ceased.) Such a shaman who had to have surgery to remove an encysted twin might wind up carrying around a rather grisly talisman.

A chimera is also exceedingly rare, but they do happen— even between fraternal twins. They can wind up as hermaphrodites, and have interesting variations in skin pigmentation. (One of these turned up in the CSI episode Bloodlines, and the show I Am My Own Twin on the Discovery Channel examines them in depth.) A single person who is actually two people could have very interesting metaphysical properties— two souls working in tandem could be much stronger than a single one. In a superheroic game, a character with Duplication could turn into two people who only bear a family resemblance to each other— and their original.