The plot could involve them teaming up to take over the Duel Monsters world. They might use their combined powers and knowledge to outwit other duelists and gain ultimate control.
One possible fanfiction could start like this: In the dimly lit tomb, Yami Bakura's spirit stirred. He could sense a new presence in the world of the living that was somehow connected to his ancient past. A young girl, with an air of mystery around her, had stumbled upon an artifact that was once part of his dark collection. Yami Bakura decided to reach out to her in her dreams, slowly luring her into his world of shadows and secrets.
Power is a very common theme. Since Yami Marik is a powerful character, many fanfictions explore how he uses his power, gains more power, or loses it. Another common theme is revenge. Given his backstory, it's often a part of the story. For example, he might seek revenge on those who wronged him in the past.
Yami Bakura x OC fanfiction often explores unique relationships. In these stories, the OC (original character) can bring new dynamics to the relationship with Yami Bakura. The OC might be designed to have a special connection with him, perhaps being able to understand his complex nature. Some fanfictions may focus on the power struggle between them, while others might delve into a more romantic or platonic bond. It really depends on the author's vision and the direction they want to take the story.
One common theme is the allure of the dark side. Yami Marik is a dark character, and many fanfictions explore how the reader is attracted to his darkness. For example, in some stories, the reader might be initially scared but then gradually becomes fascinated by his power and mystery.
I really like 'Yami Marik's Redemption in Love'. In this fanfiction, the author shows how the reader can gradually change Yami Marik for the better. It has a lot of emotional depth and the interactions between the two characters are very engaging.
You could have an OC who is a powerful magic user. The OC stumbles upon Yami Bakura's lair while exploring an ancient ruin. Yami Bakura, seeing the potential in the OC's powers, tries to make a deal with them. The OC has to decide whether to side with Yami Bakura's dark plans or use their own powers to stop him.
Well, in many Yami Bakura x Reader fanfictions, the setting often plays a crucial role. For example, some are set in modern times where the reader has to deal with Yami Bakura's presence in a normal world. Others might be set in a more fantasy - like ancient Egypt. A popular one is where the reader is a reincarnation of someone from Yami Bakura's past, and that connection drives the whole story forward.
One popular trope is the 'enemies to lovers' situation. The OC starts off seeing Yami Bakura as a threat but gradually falls for his mysterious charm. Another trope is the 'chosen one' trope where the OC has some special power or destiny that is intertwined with Yami Bakura's. Also, the 'soulmate' trope can be found, where they are fated to be together in some way.