Who might be the key characters in a 'Naruto Captured by Akatsuki' fanfic?

It could be other villages as well. Since Naruto has made friends and allies from different villages during his adventures. For example, the Sand Village might send some of their ninja to help, considering Naruto's relationship with Gaara.

Sasuke could be a likely candidate. Despite their differences, Sasuke and Naruto have a deep connection. He might hear about Naruto's capture and come to his rescue, driven by their past friendship and the rivalry that also binds them.

In a 'Naruto Captured by Akatsuki' fanfic, Naruto might be tortured for information about the Nine - Tails. The Akatsuki are known for their ruthless ways to extract tailed - beast power. They could try to break his spirit and make him cooperate.

It's possible that some unexpected characters could come to Naruto's rescue. For example, an old enemy of the Akatsuki who has a change of heart. Or perhaps some of the Jinchuriki who Naruto has befriended in the past. They might feel indebted to Naruto for his kindness and decide to help him out of the Akatsuki's clutches. There could also be a mysterious and powerful hermit ninja who hears about Naruto's capture and decides to intervene for the greater good of the ninja world.

Maybe a rogue ninja group that wants to sell Naruto to the highest bidder. They see him as a valuable asset due to his strength and status in Konoha.

Maybe some of the more conservative village elders. They have always been a bit wary of Naruto because of the Nine - Tails inside him. So they might be behind his capture in the fanfiction.

Well, Naruto is obviously very popular as he is the main character of the original series. Konan also has a large following in these fanfics because of her unique abilities and her complex relationship with the Akatsuki. Pain is another popular character as he was a major figure in the Akatsuki. His ideology and power make him an interesting character to write about in fanfics related to the Akatsuki.

Pain (Nagato) is also quite popular. His ideology and his power are very appealing to explore in a fanfic. You can create stories where he has to face Naruto not just in a physical battle, but also in a battle of ideals.

Well, it could go in many directions. For one, the Akatsuki might hold Naruto captive to use him as a bargaining chip against Konoha. They could demand things like the village's secrets or other powerful ninja in exchange for Naruto's life. Or perhaps some members of the Akatsuki would have a change of heart and decide to protect Naruto instead of following their original plan.

Well, in the fanfiction, if Naruto is captured by the Akatsuki, they might try to extract the Nine - Tails from him. They could use various cruel methods. But Naruto being Naruto, he would never give in easily. He would keep fighting back with his willpower, trying to find a way to escape or at least cause some trouble for the Akatsuki members while in captivity.