The romance novel series Bitcoin Billionaires snuck into my life last month via a lockscreen ad on my e-reader, which dependably serves up teasers for sexy Kindle Unlimited stories about vampire spies who fall in love, time-traveling Scottish warriors who fall in love, and Victorian nobles who have sworn never to fall in love, but fall in love.

Jack: A Cryptocurrency Billionaire Romance (Bitcoin Billionaires Book 1)intrigued me: It was the juxtaposition of an unromantic word (“cryptocurrency”) with a romantic word (“romance,” duh). The wealth-fantasy romance subgenre is well established, of course. Fifty Shades of Grey has its mansions and private helicopter; rich guy/poor girl titles are

But the crypto billionaire distinction was something new. Have women grown weary of the idea of sex with men who made their fortunes as soulless corporate bankers, philandering rock stars, or effete starchitects? What specific kinks would this genre plumb? Would sweaty characters rip off their clothes in the heat generated by a bitcoin-mining operation? Would swashbuckling, maverick

For answers to these questions, I reached out to romance writer and Bitcoin Billionaires author Sara Forbes, whose literal job is coming up with novel ways to make people very, very rich.

“It’s the theme of money. Billionaires, specifically,” she explained over the phone from her home in Sweden. Forbes produces an average of six books a year under several pen names — including “Sara Forbes,” which, with its whiff of wealth, is probably not an accidental choice for her tales of the absurdly rich and those whose loins burn for them — both for a major trade publisher and self-published on Amazon Kindle.

“It’s a highly popular genre,” she said. “The trope of the rich person sweeping the poor person off her feet; usually the woman is the poor person. You see it from Cinderella to Pretty Woman.”

Forbes, who is Irish, started Bitcoin Billionaires after completing a four-part series, brilliantly and punnishly titled Endowed, about young members of the British peerage in a contemporary setting. Inheritance took care of where to find their seductive piles of money at such a young age. With Bitcoin Billionaires, she was looking for another source of wealth.

“I wanted it to be realistic, and I wanted the heroes to be attractive,” she explained. How could her heroes be under 40 and fantastically wealthy without having inherited the cash or — an idea she considered but rejected for character reasons — being perhaps a ruthless, workaholic startup founder?

“How would they be that rich, and still be that young and still have their ideals intact?” she said. “That meant reading up on bitcoin.”

The plot of the series revolves around a secret cabal of investors who bought bitcoin when the price was in the single digits and now, in the present day — after something like 6000% growth over a decade or so — collectively holds enough of the world’s available bitcoin wealth to actually manipulate the market. Each one will eventually get his own erotic book; so far there are two, with a third being teased in the Kindle store.

The “intact ideals” that Forbes mentioned come in because the group, or at least some of them, want to use the money to “do something to change the world for good,” said Forbes. The highest-minded real-world crypto and blockchain evangelists proclaim that money untethered from government and a network of distributed ledgers will reduce inequality and transform industries. Like them, these guys are less Silk Road swashbucklers and more (the sexy version of) Bill Gates do-gooders of their generation.

Of course, there’s some plot-enhancing tension. “To maintain and grow their investment, they have to manipulate the market,” Forbes says. “So I explore ideas like how much manipulation is ethical if they’re using the money for good causes.”

The idea of ethical wealth comes up repeatedly in other works of bitcoin-themed Kindle erotica. In Bitcoin Billionaire’s Babysitter, by a writer named Flora Ferrari who has close to 60 titles in the Kindle store, the bitcoin billionaire in question actually sells his business to semi-mythical bitcoin inventor Satoshi Nakamoto — apparently, this loverboy is the only one in the world who knows his true identity — in order to provide for a friend’s tragically orphaned daughter. And, in a fairytale twist, he doesn’t reveal the extent of his extreme net worth to the girl’s babysitter until he knows “her intentions are pure and true.” Meanwhile, the protagonist of Brooklyn Madison Lee’s Dating the Bitcoin Millionaire woos his lady friend (weirdly, also his babysitter — sensing a theme here) by offering to bankroll her in starting “a charity that uses blockchain technology.”

The running theme points to a sort of moral calculus of arousal. Like Forbes said, the rich person sweeping the poor person off her feet is a dependable turn-on: money and its associated power have titillated consumers of romantic stories for literally centuries. In counterpoint, though — and perhaps particularly so to the millennial reader, who dozens of marketing reports have identified as valuing social responsibility — massive global wealth inequality is a huge boner-killer. Adding a dash of altruism (even Christian Grey apparently gives millions to abating world hunger) mitigates the sense that the one per cent is not as sexy as it used to be.