The Sith could still be antagonists. Even though Anakin has turned away from the dark side, there might be remnants of the Sith order who want to see his rule fail and plunge the galaxy back into chaos. They might try to manipulate events and turn Anakin's own people against him.
Some of the more power - hungry senators could be the main antagonists. They were used to having a lot of control before Anakin and Padme became emperor and empress. Now they feel threatened by the new order that Anakin and Padme are trying to establish, which focuses on fairness and equality, so they plot to undermine their rule.
A group of rogue Force - users who oppose the new regime of Anakin and Padme could be the antagonists. These Force - users might have their own ideas about how the galaxy should be run and think that Anakin and Padme are too soft or too controlling. They start a rebellion against the imperial couple, causing a lot of unrest in the galaxy.
One possible plot could be that after Anakin turns away from the dark side, he and Padme work together to bring a new era of peace and prosperity to the galaxy. They use their combined influence to reform the Senate, improve relations between different planets, and promote the growth of the Jedi Order in a more balanced way.
The Akatsuki could still be a major antagonist. Even if Naruto is emperor, they might oppose his rule as it goes against their own goals of chaos and obtaining the tailed beasts.
Obi - Wan Kenobi would be one. He's Anakin's master, and in the fanfiction, he might suspect something about their relationship and have to decide whether to support them or uphold the Jedi Code.
Well, Padme could try to fight Anakin to stop him from further embracing the dark side. She might use her diplomatic skills and love for him as weapons. For example, she could tell him how their unborn child would grow up without a father if he continued down this path.
As Padme is pregnant, Anakin may start to think more about his future and his place in the galaxy. This could lead to deeper conversations between them about their values and what they want for their family. Their relationship will grow as they both adjust to the idea of becoming parents and all the responsibilities that come with it. They'll have to support each other through the physical and emotional changes that Padme is going through, and also deal with the external threats to their family.
They might be shocked by the advanced technology. The future could have flying cars and huge skyscrapers everywhere. Anakin's Jedi skills might be seen in a new light, and Padme could be amazed at how society has evolved in terms of equality and governance.
Perhaps in the fanfic, Anakin has already fully embraced the dark side when Padme arrives on Mustafar. He shows her his new powers, thinking she will be impressed. But Padme is horrified. She tries to use their bond to reach the old Anakin inside. Meanwhile, the volcanic landscape of Mustafar could add a sense of danger and doom to their encounter, as if the planet itself is a symbol of their relationship falling apart.
One great 'Anakin and Padme fanfic' is 'A Love Beyond the Stars'. It beautifully captures their relationship, from the initial attraction to the deep love they share. The way it describes their interactions in the Star Wars universe is really engaging.
One great Anakin and Padme fanfic is 'Love in the Midst of the Clone Wars'. It beautifully captures their complex relationship during that chaotic time. The author does an amazing job of portraying Padme's strength and Anakin's inner turmoil.
I really like 'Padme and Anakin: The Untold Moments'. This fanfic focuses on the small, intimate moments between them that the movies might not have fully explored. It shows their relationship growing from a simple attraction to a deep, complex love, adding more depth to their characters.