Well, we can assume that the main characters are from RWBY, so the four huntresses - in - training are probably in it. Ruby Rose, with her silver eyes and scythe - wielding skills. Weiss Schnee, the ice - using heiress. Blake Belladonna, the cat - faunus with her dual - wielding skills. Yang Xiao Long, the brawler with her gauntlets. And then there's the titular mystical merchant who would play a crucial role in the story, perhaps as an ally, a foe, or something in between.
In this 'rwby the mystical merchant fanfiction', it could center around the merchant as a sort of catalyst for change in the RWBY world. The merchant might have knowledge that no one else does, and this knowledge could be the key to solving some of the major problems in the story. For example, they could know about the origin of the Grimm and how to defeat them once and for all. The fanfiction might explore how the RWBY characters try to obtain this knowledge from the merchant, and what they are willing to sacrifice in order to get it.
I'm not sure specifically as there are many possible interpretations in fanfiction. It could still feature Ruby, Weiss, Blake, and Yang as main characters, but with a plot centered around dilation. For example, Ruby might be the one to first notice something strange related to dilation and lead the team to investigate.
I don't know for sure without reading it, but it could feature the main RWBY characters like Ruby, Weiss, Blake, and Yang. Since it's a fanfiction, there might also be an original character who is the'stray' that the story focuses on, and this new character could interact with the main RWBY quartet.
Obviously, Cliffjumper is one of the main characters. In most of these fanfictions, he is the one bringing his unique set of skills and personality into the RWBY universe. Then there are the main RWBY characters like Ruby, Weiss, Blake, and Yang. Ruby with her leadership and scythe - fighting skills, Weiss with her Glyphs and swordplay, Blake's stealth and katana - using abilities, and Yang's brawler - like combat style often interact with Cliffjumper in different ways in the fanfictions.
In most 'rwby yellowbeard fanfiction', Yellowbeard takes center stage. He's the one with the unique look and backstory. But the RWBY girls are essential too. Ruby with her leadership skills, Weiss with her grace and combat abilities, Blake with her stealth, and Yang with her strength. There may also be other characters from the RWBY universe that pop up, like Professor Ozpin or Qrow Branwen, who might interact with Yellowbeard in different scenarios.
In some RWBY Anbu fanfiction, there could be an original character who is part of the Anbu. This character might be the central focus, with their backstory and relationships with both the Anbu and the RWBY characters being explored. For example, an Anbu character who was once a student at Beacon but had to leave for some reason and now returns as an Anbu member. They would then have complex relationships with the RWBY characters based on their past and present.
Since I haven't read it, I can't say for sure. But it might include the grandmaster as a main character. There could also be some of the original RWBY characters like Ruby, Weiss, Blake, and Yang, who interact with the grandmaster in different ways, either as students, allies, or opponents.
Often, the main characters in grandmaster RWBY fanfiction include the well - known characters from the RWBY series such as Ruby, Weiss, Blake, and Yang, but in their grandmaster versions. They have enhanced skills and more responsibilities.
Often, the main characters can include the Dullahan themselves. They are usually unique in appearance, with their headless form being a distinct feature. Another main character could be Ruby, as she is one of the central figures in RWBY and might interact with the Dullahan in various ways, like in combat or during a mission.
Typically, you'll find Ruby Rose as one of the main characters. She's a key figure in RWBY, and in the fanfiction, she often interacts with the ladybug - themed elements in interesting ways.