Two years ago, Anna Todd was a 23-year-old Army wife living at Fort Hood, attempting to be a college student. “I had no clue what I wanted to do,” she says over a honey-cream latte at Dominican Joe’s, a coffee shop near her new home in South Austin. “I tried nursing, I tried science, I tried English. I just kept bouncing back and forth.”

But one thing she knew about herself was that she loved to read. And like most millennials, she did much of her reading on her phone. She was particularly taken with Wattpad, a social platform bursting with “fan fiction”—stories inspired by celebrities, films, TV shows, or other books. Eventually, she decided to try her hand at being a Wattpad author, and in early 2013 started writing After, a work of fan fiction, inspired by the boy band One Direction, about Tessa, a college student who falls for a hard-drinking lout. Todd gave Tessa’s love interest the name Harry Styles, after a much-beloved member of One Direction.

Because she wrote many of her early entries on her phone, they were full of typos. “It’s so terrible,” she says. But that didn’t bother her readers. By July of last year, After had drawn more than a million “reads.” Today, according to Wattpad, it has more than a billion, making After Wattpad’s most popular story. Todd’s Twitter account has 200,000 followers. Her Instagram account has nearly 300,000.

New York publishing giant Simon & Schuster quickly came calling and in May of this year signed her to a $600,000 deal. After, the first book in what is now a series, was released in paperback on October 21. After We Collided, After We Fell, and After Ever Happy, which follow the steamy ups and downs of Tessa and Harry’s relationship, will appear in November, December, and February. A movie option is in the works.

Much of this success stems from the fact that One Direction fans are hungry to read anything about their idols, even (especially?) erotic fantasies. But the flip side is that many One Direction fans are extremely protective of their idols. One irate Styles fan has launched the website, and angry rumors are being spread on Twitter under the hashtag #SuspendAnnaTodd.

Harry’s name has been changed to Hardin Scott in the Simon & Schuster edition, but that hasn’t stopped the anti-Todd forces, who worry that After will bring Styles, the “sensitive” member of One Direction, to tears (“If you mess with my baby and make him cry because of your trashy story you’re gonna pay with your life!” wrote @HarrysKitten44). Todd isn’t buying it. “Fan fictions are an alternate universe,” she says, a place where readers can indulge in fantasies about people they adore from afar, and then step back into the real world when they put their smartphones down.

“I love Harry Styles,” Todd insists. “He’s one of the nicest people in the entire world. I wrote a story about a character who looks like Harry Styles. But it has nothing to do with Harry Styles at all.”