There was a brief war, but the Martians won, and converted most of the human population to breeding females. A few human males were kept as exotic pets of a sort, and breeding stock to create more human males, if mostly only so that rich Martians could pay for the pleasure of making women out of them personally.
And that was the fate of Alex. It was just Alex, no last name. Slaves didn't have last names. Alex had been lucky enough to have been used as a male breeder for a while, but no good thing lasted forever for a slave. The Martian overlords made sure to convert all of their male breeders into females before they got too old, so that all the slaves would know their place and inevitable fate.
And now Alex's time had come, and his days as a male likely numbered in the single digits. He found himself on a pleasure cruise for extremely wealthy Martians, serving drinks in a bikini that for the moment looked ridiculous on his male frame, but would likely fit soon enough. He knew that any of the Martians that leered at him as he worked might choose to buy him and make him into their personal female fucktoy. Even if none of them bought him, by the end of the cruise all the Martian pheromones in the air would slowly have changed him into a horny female anyway, now that they'd stopped administering the antidote to him. He looked down at his erection: a result of those very pheromones was that he was always hard. It was embarrassing to have it on display, it was embarrassing how small it was compared to Martian cocks, and it was embarrassing that it was just slightly smaller today than it was yesterday.