In Serenity, they can work. Within the womb of the (mother)ship they both love so much, surrounded by the only people who really know them (the only family either one of them have), safe in the absolute knowledge of their own places, they can kiss and flirt and yell in the cargo hold, drink tea and fix dinner in the galley, make love and hold each other in her shuttle, brush hands and exchange looks as they pass in the halls.

In Serenity, they can work (but the certainty always hangs above their heads, ready to come crashing down to crush them in the end: they'll have to step out into the world someday, and what happens then?).