Well, Kabuto can be a major antagonist in such fanfictions. Since he has a vast knowledge of jutsu and was once allied with Orochimaru, he could be the one causing Naruto to almost die. He might use his medical ninjutsu knowledge to create some sort of deadly virus or poison that specifically targets Naruto's unique chakra system. Additionally, Pain is also a common one. His Rinnegan abilities give him the power to cause a great deal of destruction. In fanfictions, he could be more ruthless in his attacks on Naruto, getting him to the brink of death.
One of the most common antagonists in 'Naruto Almost Dies' fanfictions is Sasuke. Now, this is not in the context of their normal rivalry. In some fanfictions, Sasuke could be under the influence of some dark power or be brainwashed into believing that Naruto is a threat to his own goals. So, he might attack Naruto with the intent to kill. Another antagonist that shows up often is Zetsu. Zetsu, with his ability to blend in and spy, could set up elaborate traps for Naruto. He could also manipulate other characters to attack Naruto, leading to situations where Naruto almost dies.
In many 'Naruto Almost Dies' fanfictions, one plot twist could be that an unexpected ally turns out to be the one endangering Naruto. For example, a character who was thought to be on Naruto's side has been secretly working for an enemy organization all along. Another plot twist might be that Naruto's own powers backfire on him. His Nine - Tails chakra, which is usually his strength, could suddenly become uncontrollable and start to harm him instead of protecting him. And sometimes, a character from Naruto's past that was forgotten or thought to be dead resurfaces and is the cause of his near - death situation.
They exist to add more drama and tension. Hermione is a beloved character, and putting her in a life - threatening situation amps up the emotional stakes for the readers.
Another reason is that it allows for different interpretations of the magic in the Merlin universe. When Merlin is in a life - or - death situation due to his magic or something related to it, the fanfiction can introduce new concepts about how magic works, what its limits are, and how it can be both a curse and a blessing. This exploration of magic is very appealing to fans of the show.
One popular 'Merlin almost dies' fanfiction might be 'The Brink of Eternity'. In this fic, Merlin is poisoned during a battle and his friends race against time to save him. It's full of intense moments and shows the deep bond between the characters.
The Akatsuki as a whole could be antagonists. In fanfictions, the Akatsuki might be interested in the power of Naruto's Evil Rinnegan. They could try to capture him to extract the power or use him in some way for their own goals. Pain, being a powerful member of the Akatsuki, could also be a specific antagonist. His own ideology about pain and peace might clash with Naruto's new, potentially more chaotic state with the Evil Rinnegan. Additionally, new original antagonists created specifically for the fanfiction could be common. These could be dark, powerful figures who are drawn to the power of the Evil Rinnegan and want to either possess it or destroy Naruto to prevent its misuse.
Fanfictions about Naruto being neglected and nearly dying can be quite intense. Some might depict him being pushed to the brink by the lack of support from the village. For example, he could be deprived of proper training or basic necessities. However, these situations usually lead to Naruto's character growth in a different way than in the original series. He might form unexpected alliances with outcasts or find new powers within himself.
Danzo could also be a common antagonist. He was very power - hungry and had his own dark secrets. In a time - travel scenario, he might view Kakashi and Naruto as threats to his control over the Hidden Leaf Village in the past. He could try to eliminate them to maintain his grip on power.
Pain is often one of the main antagonists. Since in the original story, Pain was the one who ultimately killed Jiraiya. So in fanfictions where Naruto saves Jiraiya, Pain is a natural choice to be the bad guy. Another common antagonist could be Orochimaru. He had his own vendetta against Jiraiya and the Hidden Leaf Village. He might be trying to use Jiraiya for some evil experiment or to gain access to the secrets of the Sage Mode.
Another common antagonist could be a powerful and mysterious dark wizard - like figure who has an interest in Hinata's unique abilities. This figure might be from a far - off land and has come to the Naruto universe specifically to capture Hinata. Naruto has to face this unknown and powerful foe to save her, which usually involves a lot of adventure and discovery as he tries to understand the enemy's powers.
The other Avengers would also be likely to save him. Captain America, for instance, with his leadership and combat skills, would lead the charge to rescue Tony. Bruce Banner could use his scientific knowledge to figure out what's wrong with Tony if it's a scientific or medical issue. And Thor, with his godly powers, could provide protection or use his lightning to jump - start Tony's arc reactor if it's failing. Also, in some fanfictions, new characters created by the author might step in to save him, like a brilliant young scientist who idolizes Tony and has a unique solution to his near - death situation.