As has been noted elsewhere
, pon farr
a sexual drive but a compulsion to mate.
Necessary to keep the Vulcans from "logicking themselves into extinction", in one Terran's words, pon farr
preserves the Darwinian need to reproduce
and pass on one's genes to the next generation. As such, it is an exclusively heterosexual
phenomenon – any instincts which a Vulcan might have in any other direction are thoroughly repressed along with all other emotional feelings and urges. Homosexual behavior within "normal" Vulcan society (longstanding rumors surrounding Ambassador Spock and Admiral Kirk notwithstanding) is therefore completely unknown. After all, in the words of a particularly libertine Deltan
, "someone has to balance out the more 'sexually mature' races."
There still exists a small, little-known minority of Vulcans called the V'tosh ka'tur who allow themselves (in secret and/or exile) to experience some emotions and physical drives as a complement to their Vulcan logic. It is possible that some of the V'tosh ka'tur also indulge in sexual experimentation beyond the standard "mating practices", but it cannot be confirmed as little information about them is available to researchers or the general public.
In the alternate universe from which Evil Storvik originates, Vulcans also suppress emotions and sexual urges – as with many other things between that universe and ours, the reasons are different but the results are the same. Some sexual behavior is still practiced by Mirror-Vulcans for various reasons – as in this universe, Vulcans operating as undercover agents may have to engage in sexual behavior (Evil Storvik, as a trained counter-espionage agent, can be assumed to have been trained in "multiple techniques and a broad variety of pleasuring"); it is also possible (but unconfirmed) that Vulcans may participate in the sexual dominance of underlings, or the use of rape as a punishment or interrogative technique, that occurs in the Mirror Universe. The default condition there, however, as here is that Vulcans engage in sexual activity primarily (if not exclusively) during the throes of pon farr in order to perpetuate the species.