Two “Star Trek” plot devices proved a gift for writers struggling to bring their avowedly heterosexual heroes to a mutual understanding. As a half-Vulcan, Spock is able to establish a telepathic link with others simply by touching them (the “mind meld”). In one slash fic after another, some emergency makes it essential that he mind-melds with Kirk – and the pair discover that their passion is reciprocal. Pon farr, or “mating time”, is an aspect of Vulcan biology: every seven years, Vulcans must mate or die. Leave the two men stranded on an uninhabited planet; put the Enterprise’s transporters out of action – and let Kirk’s concern for his first officer do the rest.