Fanfiction communities are attempting to root out writers using generative AI to produce fanworks, but the detection methods being implemented are questionable, and any fanfic writer could be caught in the crossfire. Broad distaste around the use of Claude, ChatGPT, and other AI tools has long been present in creative communities, including fanfiction, where readers and writers have shared tips for spotting supposedly AI-generated works, citing anything from em dashes to purple prose.
On June 29th, an anonymous X account called @heatedrivalryai posted a skin — similar to an extension — for the fanfic repository Archive of Our Own (AO3) that purportedly identifies coding artifacts left behind by Anthropic's Claude bot. When Claude-generated text is pasted directly into AO3, it is wrapped by a Claude-injected code called "font-claude-response-body," the account said, and the skin turns the entire background red when it detects the code. The Verge tested the skin and confirmed it triggered on Claude-generated text pasted straight from the chatbot, but not on the same text pasted without the code.
The detector was accompanied by examples of fanfic where the artifacts were spotted, and the anonymous creator said the goal was to demonstrate the system works, not "create an environment of mistrust or accuse particular users." Nonetheless, fanfic communities have mobilized to publicly name and shame writers whose published works were flagged by the tool.