One common theme might be power and transformation. The silver flame across the body could symbolize a new power or a transformation that the character is undergoing. Another theme could be struggle, like the character trying to control or come to terms with this new silver - flamed aspect of themselves.
Common themes in such a fanfic can be quite diverse. There could be a theme of heroism, where the character with the silver flame uses it to fight against evil or protect others. Friendship is also a possible theme. The friends of the character with the silver flame may react in different ways, some supportive, some afraid. Another theme could be mystery. The origin of the silver flame and what it truly means could be a mystery throughout the fanfic, driving the plot forward as the character tries to uncover the truth about it. There might also be a theme of sacrifice, if the character has to give up something to control or utilize the silver flame effectively.
Well, I haven't read that exact 'rwby silver flame across his body fanfic' in particular. But generally, to find good ones, you can also check out some RWBY fan communities on Reddit or other forums. There, fans might share and recommend fanfics with such elements. Another option is to follow some RWBY fanfic writers on social media platforms as they may post about their works or recommend others.
One possible plot could be that the character with the silver flame covering his body is a new, powerful antagonist. He might be on a mission to destroy a certain part of Remnant. The heroes of RWBY then have to figure out how to stop him. Maybe the silver flame gives him unique abilities like the power to fly or to be immune to certain types of attacks.
Perhaps he is a spirit from an ancient time. The silver flame is a remnant of an old magic that has resurfaced. He has been awakened in the present day of RWBY's world and is trying to understand this new world while also dealing with the power of the silver flame that he doesn't fully comprehend.
In the fanfic, the Silver Flame could be representing an underdog force. Their victory over the top huntsman might symbolize the triumph of the underestimated. They could have used their wits and the element of surprise. For example, they might have feigned weakness at first to make the top huntsman overconfident, and then launched a sudden and powerful counter - attack using their unique skills and abilities.
Ruby could be a great main character for a 'rwby silver flame fanfic'. Given her natural leadership and combat skills, she could be on a quest to understand and control the Silver Flame, perhaps believing it could be a new weapon against Salem.
Another plot idea could be a character who is mysteriously connected to the Silver Flame. They could have powers that are enhanced by it and have to hide this fact from others for some reason, like fear of being experimented on. For example, a new student at Beacon Academy discovers this connection and has to navigate through the challenges while keeping it a secret.
The Silver Flame is surely a main character. There could also be characters related to the Silver Flame, like their comrades or mentors who might have influenced their growth and abilities, which in turn helped them to defeat the top huntsman. And of course, the top huntsman is a key character as the one being defeated.
One common theme is the struggle with the flame power. In many fanfics, the characters have to come to terms with the power they are bound to. Another theme is redemption. The main characters often seek to atone for their past mistakes or actions.
One common theme is adventure. Given the nature of the 'across the sun' concept, it's likely that the fanfics will involve characters going on exciting journeys. Another theme could be self - discovery. Characters may find out more about themselves as they face the challenges in this unique world. Also, friendship is often a theme. Characters might form strong bonds with each other while dealing with the various situations in the 'across the sun' fanfic.
A common theme is the struggle against the forces of evil. In the RWBY setting, there are various threats. The knight and his maiden often find themselves in the middle of battles against these forces. Their bond is tested and strengthened as they face these challenges together. It shows how they rely on each other and grow as characters while fighting for what is right.