One possible plot twist could be that Cheetara discovers Mumm - Ra's true nature only after the marriage. Maybe she thought she could change him, but then realizes he has some dark ulterior motives that put her and her friends in danger.
Perhaps a plot twist is that the marriage is part of a grander plan by an even greater evil force. This force manipulates Mumm - Ra into marrying Cheetara, thinking it will give him more power, but in reality, it's a trap to control both of them and use their combined influence for its own malicious purposes.
The other characters would likely be very shocked. For example, Lion - O, who might have had feelings for Cheetara, would be heartbroken. And the Thundercats as a whole would be distrustful of Mumm - Ra and might see Cheetara as a traitor.
Another possibility could be Monkian. He might suspect that Cheetara is not fully loyal to Mumm - Ra and start his own investigation. His actions could put Cheetara in danger as she is already in a difficult position as a servant. And if he finds out the truth, he could expose her to Mumm - Ra, which would be a huge threat.
In a fanfiction, the Naruto - Mumm - Ra fusion could be described as a being of contradictions. It would have Naruto's kind heart warring with Mumm - Ra's evil intentions. Physically, it could be like a mummified ninja, with Naruto's features distorted by Mumm - Ra's presence. Its abilities would be a chaotic combination. It could use Naruto's shadow clones but with a dark twist from Mumm - Ra. And when it uses its power, there could be a mix of Naruto's bright chakra and Mumm - Ra's inky black energy.
If Naruto and Mumm - Ra fused, it could result in a very unique appearance. Naruto's spiky hair and orange jumpsuit might mix with Mumm - Ra's skeletal and mummified look. In terms of powers, Naruto's Rasengan could potentially be infused with Mumm - Ra's dark energy, creating a super - powerful and dangerous attack. This fusion would also likely have a complex personality, as Naruto is generally upbeat and Mumm - Ra is full of malice.
Perhaps Willa discovers that she has some sort of special power that is activated by Cheetara's kiss. But this power comes with a price, like she has to leave her home or give up something she loves. Another plot twist could be that Cheetara kisses Willa thinking it will save her, but in fact, it puts Willa in more danger as it attracts the attention of some evil force in the story.
Well, it could be that Hermione is under a spell when she marries Rowle. The fanfiction could then revolve around how she breaks the spell and what she does after realizing she's been forced into this marriage. She might find that Rowle has some redeeming qualities despite the situation, and they could either part ways amicably or decide to work on a real relationship.
One possible plot twist could be that the Death Eater she marries is secretly a double agent. He might be working against Voldemort from within the Death Eater ranks and Hermione discovers this. Their relationship could start as a way to get closer to the Death Eater secrets but then turn into real love.
In a 'cheetara gets betrayed fanfiction', perhaps her closest friend reveals her secrets to her enemies. This could lead to her being in great danger as her foes now know her weaknesses. She might feel isolated and have to struggle alone to overcome the situation.
Maybe in the fanfiction, Cheetara discovers a strange portal and ends up in the Naruto universe. Naruto is initially suspicious but soon realizes she's not a threat. Cheetara is intrigued by Naruto's chakra and his ability to use ninjutsu. They start training together, with Cheetara teaching Naruto some of her speed - based combat techniques and Naruto showing her how to manipulate chakra more effectively. As they face various threats in the Naruto world together, their bond grows stronger.
Well, one possible plot twist could be that their secret relationship is discovered by a jealous rival. This rival might then try to break them apart by spreading false rumors about them. Another twist could be that they are from different social groups or families that are feuding, adding a Romeo - and - Juliet - like element to their relationship. And perhaps a third twist could be that they have to keep their relationship secret because one of them is involved in some sort of dangerous or top - secret mission, and the relationship could endanger it.