Neko Dynasty
The Neko Dynasty was a June 2016 fantasy roleplay (RP) based on BHH which was one of the Acteriendian BHH roleplays and later the basis for the Suijing Cycle. In addition to the RP, there was a narrative story written by Kerry using dialogue from a private RP between Rob and Cat, and the text of this story survives (whereas the RPs have been lost).
The Neko Dynasty was set on a forested planet, involved both magic and interplanetary travel, and had an Ancient Chinese and Japanese aesthetic. The intention may have been that it was set in the same universe as BHH but far in the past. Robert and Cat used their BHH key characters, Ro Elluna and Raven Olympia, though Ro was now a neko (anime cat girl) and was played as softer and kinder—more like Cat's later character Lyra Felise. Kerry used a new character, Ying Zheng, on whom his later character Kensaki Zihau was based.
The premise of the cycle was that nekoes were being persecuted, so Ro and her semi-romantic partner Raven had fled to a "neko sanctuary" run by Ying, a scholar who wished to keep magic alive. Magic was presented as an ancient, dying art that had been mostly forgotten, lingering only in backwater places like Zheng's sanctuary; it was also taxing to perform. Raven and Ro could use basic magic like teleporting or conjuring fire, particularly in combat, and Zheng had more sophisticated magic that he had learnt from ancient scrolls. Separately, Ro could read the future via violent, painful visions, and she & Raven could merge into a powerful "fusion" called the Raveline or the Rovalane.
In real life, Rob had an obvious crush on Cat, and the potential for snide remarks based on fusion did not go unnoticed: "Raveline" became a real-life ship name for the two and a meme that endured into at least 2018. Indeed, the broader principle of Rob and Cat doing anime catgirl RPs in private messages caused some amusement, and Rob's insistence in response to Raveline jokes that "fusion isn't sex" because something of a meme in its own right.