Not since 1999 have two titans of the best-seller lists clashed so spectacularly. Back then, novelist Nora Roberts, already a juggernaut with 35 million books in print, sued Janet Dailey, one of the most successful romance writers of the late 20th century, for copying passages and ideas from her published works. The two authors settled out of court, but followers of the genre still talk about the case; Roberts described the experience of being plagiarized as “mind rape.” So it’s unsurprising that when No. 1 New York Times best-selling author Sherrilyn Kenyon sued No. 1 New York Times best-selling author Cassandra Clare, filing a complaint of copyright and trademark infringement on Feb. 5, the news spread fast. At issue, to the puzzlement of many observers, isn’t word-for-word plagiarism, but what looks like Kenyon’s attempt to claim ownership of some of the most archetypal themes in popular culture (“an elite band of warriors that must protect the human world from the unseen paranormal threat,” for example). And egging Kenyon on is a legion of implacable Cassandra Clare detractors who have had it in for the YA phenom since her apprenticeship years in the notoriously toxic subculture of Harry Potter fandom.

Kenyon has been publishing several interlocking series of paranormal romances under the aegis Dark-Hunter since 2002. Clare writes urban fantasy for young adults; her best-known series is a six-book sequence titled the Mortal Instruments, the first of which, 2007’s City of Bones, was made into a (not very successful) Hollywood film in 2013. Both Kenyon’s and Clare’s series feature secret societies of supernatural crusaders tasked with protecting the unsuspecting human race from predatory demons. Kenyon’s are “dark-hunters”; Clare calls her group “shadowhunters.”

Currently, Mortal Instruments is enjoying a TV reboot as a series titled Shadowhunters on the cable channel Freeform (formerly ABC Family). By all appearances, the TV series precipitated Kenyon’s complaint (the text of which has been posted online by romance novelist and former attorney Courtney Milan), but her grievance has been stewing for a long time. According to the document, 10 years ago, “distressed fans” informed Kenyon that Clare was shopping a manuscript for a first novel (eventually published as City of Bones) in a projected series about a group she called “darkhunters.” Kenyon claims that she protested the use of this name and that Clare agreed to change it. The complaint also alleges that despite “continuous assurances from CLARE and CLARE’s publisher that she/they would not expand the use of the ‘shadowhunters’ term or adopt it as a trademark, CLARE has persisted over time in expanding her use of the term ‘shadowhunters’ from a mere description of her protagonists, first to a tag line on the cover of her works and eventually to a complete rebranding of her works so as to be confusingly similar to the Dark Hunter Series.”

Clare’s attorney, John Cahill, issued a statement on Friday refuting these charges. Not only was there no such agreement, he told me, but the two women have never communicated at all. “They’ve never spoken, never met, and Cassie has never read her books,” Cahill said. In an email, Holly Black, a novelist and longtime writing partner and friend of Clare’s, told me that early drafts of and a proposal for City of Bones did use the name Darkhunters. However, while attending a publishing trade show in May 2006, Black was given a copy of one of Kenyon’s books and noticed that the term Dark-Hunter appeared on its cover, trademarked. “This was before any book of [Clare’s] was in print,” Black added. Cahill read aloud to me from an email that Clare sent to her then-agent, Barry Goldblatt, in which she describes Black’s discovery and both parties remark that they have never heard of Kenyon before. Implied in the emails, Cahill argues, is the decision to change the name. Black recalls helping Clare brainstorm alternative names for the group shortly afterward. (Neither author would comment on pending litigation. When asked to comment on Cahill’s statement, Kenyon’s attorney, James Mackler, replied via email, “While there may be many people commenting on the lawsuit, at this point the only official court record is the complaint that we have filed,” and reiterated the text of the complaint specifying that Kenyon demanded that the term darkhunter be removed from Clare’s book in 2006.)

Attached to Kenyon’s complaint is a detailed list of similarities between the Dark-Hunter series and Mortal Instruments. These include such motifs as objects “including without limitation a cup, a sword, and a mirror, each imbued with magical properties to help battle evil and protect mankind.” And both “Dark-Hunters and Shadowhunters have enchanted swords that are divinely forged, imbued with otherworldly spirits, have unique names, and glow like heavenly fire.”

If these tropes sound familiar to you, you’re not alone. After the Guardian wrote about the suit, my own social media feeds filled up with writers alarmed at the notion that a litigious author seemed to be claiming ownership of some very commonplace motifs of the fantasy genre. As Milan pointed out in a tweet: “95% of what she is claiming are character tropes and journeys and items from our shared literary background.” To be fair to Kenyon, her actual complaint seems to argue not that she invented these traits but that, in bulk, the similarities between the two series are significant enough to lead people to confuse them with each other. However, even her own readers find this implausible. In just one example, a commenter on an article about the suit on the pop culture website the Mary Sue wrote, “I used to read Kenyon’s series. … Not once in reading Mortal Instruments did I think of Kenyon’s work.”

The two series differ in form and tone. The Mortal Instruments features such YA standards as a group of attractive young people thrown together in stressful circumstances, spiced with plenty of angsty, will-they-or-won’t-they romantic tension extended over several books. Each of the Dark-Hunter novels centers around the courtship of a different adult couple, who, once they attain their happily-ever-after ending, serve only as background characters in the story of the couple in the next book. There’s not much sex in Mortal Instruments, although there are dark overtones of incest and sexual violence. Sex in the Dark-Hunter series is abundant and explicit but largely untouched by serious, real-world trauma or transgression. As much as the series differ from each other, they’re both very typical of their respective genres: YA urban fantasy and paranormal adult romance.

“I know Clare can be a divisive figure,” Milan tweeted, “but no one who cares about books should be rooting for her to lose the copyright claim.” Yet many are, and with a ferocious vehemence that seems out of proportion to Kenyon’s thinly supported complaint. This contingent has turned out to crow over Clare’s travails in comments threads at Entertainment Weekly, the Wrap, Interrobang, and any other publication that covered the story: “yas, sue that fucker,” reads one. “she’s had it coming for a looooooooooooooooooooooong time.” “Jk Rowling should sue this bitch as well,” reads another, “seeing as her fanfiction back in the day which became TMI was a Harry Potter fanfic and it also took things from the Dark Hunter series as well. … It’s about time she gets sued.”

This is the history that Clare seems unable to escape, whether you believe, as these commenters do, that she is a terrible person who has committed countless personal and professional misdeeds, or you think, as Clare partisans do, that she is dogged by legions of unhinged haters. Some of these critics claim firsthand experience of Clare’s wrongdoing, back in the early 2000s, when she became involved in the burgeoning Harry Potter fan-fiction community and rose to the top of a perceived social hierarchy that generated considerable resentment. “She was a BNF [big-name fan] and belonged to this clique,” Elizabeth Minkel, who writes about fan culture for the New Statesman, told me. “This happens a lot in fandom. It feels very much like high school.”

One of the first big fandoms to fully deploy the communication potential of the Internet, Harry Potter fandom was also the most infamous for its scandals, intrigues, and in-fighting—controversies that unfolded in seemingly endless discussion threads and frequently degenerated into accusations of harassment, stalking, sock-puppetry, doxxing, cyberbullying, and attempts to sabotage enemies’ real-life positions at work and at school. These saga-like feuds are referred to as wank, a word that embodies fandom’s ambivalent relationship to its own social climate. Until last year, a community named Fandom Wank existed for the sole purpose of posting mocking reports on wanks for the entertainment of the fan community at large. Yet the very ferocity that fuels wanks indicates how violently people care about what would strike most outsiders as absurdly petty offenses and disputes, like which fictional character ought to become romantically involved with another fictional character.

If Harry Potter fans generated the most epic wanks in the fan world, then Cassandra Clare was ground zero for some of the wankiest wanks in all of fandom. Clare’s fan fiction—originally published as the work of Cassandra Claire (both names are pseudonyms)—included three novels that made up the Draco Trilogy, a rewriting of J.K. Rowling’s series that pairs Harry with Hermione and Ginny Weasley with Draco Malfoy, albeit with ample homoeroticism (a fan-fiction staple) crackling between Harry and Draco. The trilogy was hugely popular, leading to much complaining about Clare’s cloyingly devoted “fangirls.” But it’s still not entirely clear from this remove just why she became and has remained such a lightning rod. It is true that Clare reproduced word-for-word passages from a traditionally published fantasy novel, then out of print, by Pamela Dean in one of her fan fictions, Draco Sinister, with only nominal citation. This is the basis on which her detractors accuse her of being a plagiarist. And having scrutinized, via the Wayback Machine, a lengthy document on the case, I do think she crossed a line in this instance. Other charges—that Clare improperly used bits of dialogue, devices, and wisecracks from TV shows and books—are baffling to anyone rooted in the broader literary culture where such allusions and quotations are considered a sign of erudition or postmodern fun. (Clare’s fiction came with notations informing readers that her work included such quotes.)

It’s worth pointing out that all of this took place within the creative sandbox of fan fiction, an amateur arena in the best (as well as the worst) sense of the word. “Borrowing lines, borrowing characters,” Minkel said when I asked her about it. “It’s complicated because it’s a world of borrowing. You’re very knowingly playing with source material.” Clare might have done wrong deliberately, or she might also have assumed a mashup freedom that the insular community of fandom was unprepared to allow her.

It’s obvious from reading old online journal entries like this one, along with the appended comments, that the animosity toward Clare sprang from much more than an incident that might be described, generously, as a youthful indiscretion. “Jesus god, some people,” one comment snips. “The bitch writes fanfiction. She’s not an actress, or a singer, and she hasn’t really done anything to help humanity. What makes her- OR her entourage think- that she’s so damn special?” Like much of this old, archived discussion of Clare from the early 2000s, current indictments of her on Tumblr show a disproportionately exaggerated fury—especially considering that, in the years since, after publishing many highly successfully books, Clare has kept her nose clean.

Some Tumblr posts also accuse Clare of “bullying” her critics, while her partisans retort that it is her critics who are guilty of bullying and intimidation. Mutual accusations of bullying are, in my experience, the point at which any Internet wank disintegrates into the unknowable, but one thing is clear: Way too much of the discussion of Clare on both sides sounds like a conversation you’d overhear from the stalls in a middle-school girls’ restroom.

How does all this ancient history relate to Kenyon’s lawsuit? Black told me she saw no connection. But it’s worth noting that Kenyon’s complaint states that the “distressed fans” who alerted her to Clare’s use of the term Darkhunter approached her in 2006. City of Bones wasn’t published until 2007. Presumably a manuscript, proposal, or perhaps even early promotional material was produced using the word Darkhunter. But these items wouldn’t have circulated widely. Yet no sooner had Clare’s publisher posted the Amazon page for City of Bones in the summer of 2006 than someone started a discussion accusing Clare of having stolen the term from Kenyon, a discussion that accumulated further postings making scornful references to Clare’s fan-fiction past and plagiarism. Perhaps these “distressed” individuals really were Sherrilyn Kenyon fans. But it does seem unlikely that they’d be avidly perusing the advance publicity for an otherwise unknown author’s first book if they were not also crusading Clare anti-fans from the community she was apparently leaving behind.

I have friends with deep roots in fandom—albeit without much connection to this particular sector of it—who believe that this is the true source of the undying animosity toward Clare: She left fandom “badly,” or, worse yet, she seemed to be repudiating her own origins in that community by changing the spelling of her name. Fan-fiction writers are routinely and viciously ridiculed and shamed for their hobby, which makes their communities especially insular and self-policing. “Back in the day,” Cleolinda Jones, a onetime regular at Fandom Wank, wrote to me, “we used to say, ‘The first rule of fanfic is, do not take money for your fanfic.’ Because the overriding fear was intellectual property holders would sue everybody and shut fandom down.” Rights-holders that once issued cease-and-desists against fan sites for using promotional photos now encourage fan art and other tributes, Jones says, but in the early 2000s, “I just really cannot overstate the sense of living on borrowed time by the grace of the IP holders.” This would explain why word-for-word plagiarism, as opposed to the transformative appropriation of another creator’s characters and setting, would seem a catastrophically reckless sin against the entire community.

Of course, Clare was reviled—and adored—in Harry Potter fandom even before the plagiarism charges against her came to light. And fan fiction itself has come a long way, spawning numerous real-world stars, fan writers such as E.L. James who move on to publish best-sellers. Clare was among the very first to do this. But the prospect of going pro and striking it rich seems to many fan-fiction writers like a serpent in the garden, corrupting what once felt like an idyllic, egalitarian gift-economy of like-minded dabblers. Once, fandom was a destination in itself; now it’s just another stepping stone for ambitious writers with their eyes on a richer prize. Like so much of the idealism of the early Internet, this, too, has become an offshoot of the marketplace. “I think what you don’t understand,” one friend told me when I expressed bafflement that Clare’s fellow fan-fiction writers didn’t view the popularity of her books as a feather in their collective cap, “is that a lot of them just feel used.” When I admitted that didn’t make sense to me, she added, “It’s hard to explain, but that doesn’t mean it isn’t real.”