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.
A fanfiction might describe the Naruto - Mumm - Ra fusion as a cataclysmic event at first. The very act of fusion could cause shockwaves in the fictional universes. The resulting entity would be a complex blend of both characters. Naruto's energetic and impulsive nature would be tempered by Mumm - Ra's calculating and malevolent mind. In terms of looks, it could be a nightmarish yet fascinating sight. Picture Naruto's hair, now a bit ragged and with a faint smell of decay. His body would be covered in a combination of his normal clothes and Mumm - Ra's tattered robes. And when it comes to power, it would be like a storm of light and darkness, with Naruto's positive chakra and Mumm - Ra's negative energy constantly clashing and sometimes combining in unexpected ways.
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.
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.
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.
The plot could change drastically. For one, the power balance in the ninja world would be severely disrupted. Enemies that were once a threat would be easily dealt with. The fusion could also change the political situation. With its combined charisma (from Naruto) and intimidating presence (from Madara), it could unite or divide the villages depending on its goals.
Well, it could be about Naruto having some special powers or a connection to Ra due to being his 'son' in this fanfiction. Maybe he has to face new enemies or challenges related to this new identity.
The fusion could be shown as a chaotic yet beautiful event. Sparks could fly from the wands as they touch, and the magic within them could seem to fight at first, like two different forces trying to assert dominance. But then, as they start to meld, the chaos gives way to harmony. The colors of the magic, say the warm red - gold of Harry's wand and the cold, steely grey of the Elder Wand, could blend into a new, unique color. And the resulting fused wand would look as if it was crafted by the most skilled wand - maker, with an otherworldly beauty and an aura of great power.
Well, in fanfiction, Naruto might make a sword that has his own personal touch. It could be made from a rare material he discovers on one of his adventures. He would probably engrave it with symbols that are meaningful to him, like the Uzumaki clan symbol. And it could be a sword that can change its form depending on the situation, like from a short sword to a long katana.
RA9 could be Markus. Since he is a central figure in the android revolution, some fanfictions might interpret him as the manifestation of RA9, bringing change and hope to other androids.
The plot might also involve Naruto learning the secrets of the Winged Dragon of Ra's power. Since Naruto is always eager to become stronger, he could study how the dragon's power works and try to incorporate some of its abilities into his own jutsu. This could lead to some really interesting battles where he uses a combination of ninja skills and the dragon's magic.