One common theme is the internal struggle. Crow has to deal with the dark powers within him while still trying to hold on to his sense of self. Another is his relationships with the other characters. It might explore how they react to his transformation and how he interacts with them as a Dark Signer.
You can try looking on fanfiction websites like FanFiction.net or Archive of Our Own. Just search for 'Crow Dark Signer Yu - Gi - Oh 5DS' and you might find some great stories.
There are many interesting fanfictions on this topic. Some might explore Carly's transformation into a Dark Signer and how it changes her relationships. For example, it could show her relationship with Jack becoming more complex as she is now on the 'dark side'.
One possible fanfiction could be about Leo's transformation into a Dark Signer. It might explore his internal struggle between the dark power and his loyalty to his friends. Maybe he starts to have visions that the dark power shows him, of a world where he rules with great power, but at the cost of losing his true self.
One idea is to have Leo's time as a Dark Signer be a sort of test. Maybe the gods or some higher power in the Yu - Gi - Oh universe are testing him to see if he can resist the allure of ultimate power. In this fanfiction, Leo would constantly be on the verge of succumbing completely to the dark, but there would be glimmers of his true self trying to break through. His duels could be a way for him to either gain more power or lose himself further, depending on how he uses his cards.
Love is also a frequent theme. Some fanfictions explore a romantic relationship between Yusei and Luna. It could start with a slow - burn attraction and develop into a deep love over time. Additionally, the theme of power is often present. Luna's psychic powers and Yusei's dueling skills can be combined in unique ways in these stories.
A fanfiction could center around a crossover where the Signers from 'Yu - Gi - Oh 5Ds' encounter characters from 'Familiar of Zero'. The two groups could team up against a common enemy. For example, they could face a powerful duelist who also has some sort of magical ability similar to that in 'Familiar of Zero'. The Signers' powers combined with the magic of the 'Familiar of Zero' characters could make for an epic story.
A really interesting fanfiction I came across was about Yusei's encounters with other Dark Signers before fully becoming one himself. It showed how he was gradually influenced by the dark forces. In some fanfictions, the author might focus on Yusei's new deck as a Dark Signer. It could have cards with darker themes and more powerful but dangerous effects. These fanfictions can offer a different perspective on Yusei's character compared to the original series.
A cool plot could be that there is a mysterious tournament that somehow bridges the two worlds. Duelists from Yu - Gi - Oh GX and Yu - Gi - Oh 5DS are invited to participate. However, it's not a normal tournament as there are strange rules and hidden agendas. The GX characters, like Jaden, bring their fun - loving and sometimes unpredictable dueling styles, while the 5DS characters, such as Yusei, bring their more strategic and high - speed dueling approaches. As the tournament progresses, they start to uncover the truth behind it and have to work together to stop those who are misusing the tournament for evil purposes.
The dark and edgy themes associated with the Dark Signers provide a lot of creative fodder for fanfiction writers. The idea of the Dark Signers being bound by a dark power and their struggle with it, or their different motives for being part of this dark group, can be explored in so many different and exciting ways. Writers can take these themes and create really engaging and thought - provoking stories that draw readers in.
One common theme is power exploration. Writers often explore how the Dark Magician's powers interact with the new world he's in. For example, in a crossover with a superhero universe, they might show how his magic compares to super strength or flight abilities.