My setting is futuristic-military: earth-born soldiers doing their tour of duty defending fledgling human colonies on other planets against aliens.
I have two soldiers who have been attracted to each other for a while, alone in the barracks showers. Sex ensues. My question is: what can they use as a lubricant?
I found that water is no good, soap is no good. Is there anything else that could be used? (For any site that recommended anything, I found two that said never to use that same thing. It left me very confused.) I should add they are not using a condom (vaccines for STDs instead). Is there any chance at all that with no condom, they wouldn't need a lubricant for anal/have options that are incompatible with condoms?
Considering the sex is based on a combination of attraction, needing to feel alive after the horror of a combat situation, and post-combat "life is too short to keep on being shy", I feel that frottage would be too intimate for the characters. Are there options other than anal that are not face-to-face, and would work with the absence of proper lubricants?