Perhaps in the fanfic, it seems like Ahkmenrah has died, but in reality, he has been transported to another dimension. Kahmunrah then has to journey to this dimension to find him, and along the way, he discovers some dark secrets about their family that change his perspective on everything.
What if Kahmunrah's attempts to take over were all a ruse to actually protect Ahkmenrah from a greater threat that he knew was coming? He played the villain so that the real enemy would underestimate him and focus on him instead of Ahkmenrah. This would completely turn the tables on their relationship and the expected plot.
A plot twist could be that Kahmunrah was actually being controlled by an ancient curse all along, and it was the curse that made him seem so evil. When Ahkmenrah discovers this, he has to find a way to break the curse and save his brother.
Another concept could be a time - travel fanfic. Kahmunrah travels to the future and sees the legacy of Ahkmenrah in the museum. He then has to decide whether to try and change history or accept the new world order. This would allow for a lot of exploration of both their personalities and how they react to new and strange situations.
Asha could be a struggling singer - songwriter. One day, she gets an opportunity to open for Starboy's concert. Starboy is initially unimpressed with her, but during the rehearsal, he hears her sing a song she wrote. He's so moved that he asks her to collaborate on a new track. As they work together, they start to fall in love, and their music reflects their new - found relationship.
A great plot point would be Tsunade getting injured on a mission and Naruto having to take care of her. During this time, they realize their true feelings for each other. Also, they could face a threat from an old enemy of Tsunade's who resurfaces. Naruto and Tsunade would then have to combine their skills, Naruto's combat abilities and Tsunade's medical and strategic knowledge, to defeat the enemy. And as a result, they decide to get married to celebrate their victory and new - found love.
In a plot, the Puppet might be trying to bring peace to the haunted pizzeria. Golden Freddy, initially reluctant, is eventually convinced by the Puppet's determination. They face many spooky and dangerous situations together, like dealing with other malevolent animatronics. As they work side by side, they start to care for each other and the pizzeria slowly becomes a less terrifying place.
A great plot twist could be that Naruto's night - turning is actually part of a prophecy that no one knew about. The village initially thought it was a bad thing, but it turns out it's the key to saving the ninja world from a greater threat. Maybe it's related to an ancient evil that only emerges during the day, and Naruto's new form at night is the only counter to it.
One plot idea could be that Batman travels back to a time when Gotham was first founded. He discovers that a powerful and corrupt group is using advanced weaponry, including guns that are way ahead of their time. To combat them, he uses his own time - traveling - acquired guns. Along the way, he has to deal with the moral dilemma of using such lethal force in a time where the concept of Batman as a non - killing hero doesn't exist yet.
Here's a plot twist: Catwoman steals a powerful artifact that she believes is being misused by a powerful figure in Gotham. However, it turns out that the artifact is the key to a much greater threat that only Batman can understand. Now Catwoman has to work with Batman to put the artifact back where it belongs and stop the impending doom, all while dealing with their complex relationship.
I'd say 'Shifting Sands' is great for plot twists. It starts off with a seemingly simple premise but then throws in these mind - blowing twists. The relationship between Stiles and Derek is constantly evolving because of these twists, which makes for a very engaging read.
A great fanfic concept would be Naruko and Tsunade going on a diplomatic mission to a neighboring village. Along the way, they face various challenges that test their diplomatic skills, and in the process, they develop a deeper understanding and respect for each other's abilities.
One possible plot twist could be that Castiel kidnapped the character not out of malice but to protect them from a greater threat that the other characters are unaware of. For example, there might be a powerful and hidden enemy that has targeted this particular character, and Castiel believes that by taking them away, he can keep them safe.