Naruto could also rely on his friends. Even though he is kidnapped, his friends would surely be looking for him. They might create a diversion or find a way to communicate with Naruto. Naruto could then coordinate with them to escape. For example, Sasuke could arrive at the right moment and together they could overpower Madara and escape.
Naruto could use his shadow clones. He might create a bunch of clones to distract Madara while he finds a way to break free from whatever is binding him. Since Madara is a powerful opponent, Naruto would need to be very strategic with his clone usage.
Perhaps Naruto taps into a new form of his chakra, like a deeper level of the Nine - Tails' power. This sudden increase in power could allow him to break Madara's hold on him and then make a run for it. He might also use the environment to his advantage, like using the terrain to hide or set up traps for Madara.
Naruto could use his shadow clones to create a diversion. He might make a bunch of clones and have them attack the Akatsuki members in different directions while he tries to find a way out. For example, he could use the chaos to search for a hidden passage or a weak spot in their hideout.
Another way Naruto could escape is by making an unexpected alliance. There might be other characters in the fanfiction who are also against Obito. Naruto could convince them to help him. For example, if there are some anti - Obito ninjas in the area, Naruto could appeal to their sense of justice and work together with them to escape.
She could use her shadow clones. Female Naruto might create a bunch of clones to distract Orochimaru and his minions while she makes her escape. Since she is known for her large chakra reserves, she can afford to create many clones at once.
There could be a shift from enmity to a begrudging respect. Madara has always been a powerful and feared foe, but with Naruto being stronger, Madara may have to accept Naruto's superiority. Naruto, on the other hand, would likely try to understand Madara's motives better and might try to reform him rather than just defeat him.
Well, in such a fanfiction, it might start with Naruto being in a situation where he becomes Madara's pet. Maybe at first, Naruto is defiant but as time passes, he could start to understand Madara's motives in some strange way. Madara, on the other hand, might initially see Naruto as just a possession but gradually develop a sense of attachment. It could be a really strange and complex relationship that unfolds as the story progresses.
In fanfiction, Naruto has a lot of ways to escape from Akatsuki if kidnapped. He could wait for an opportunity when the Akatsuki members are preoccupied with their internal disputes. Since he has a strong bond with his friends in Konoha, they might be on their way to rescue him. Naruto could also use his unique Uzumaki bloodline abilities, like his strong life force, to endure any torture or imprisonment until he finds a way to get out. He might even discover some secrets about the Akatsuki during his captivity that could be used to his advantage.
He could use his Rasengan. If he manages to gather enough chakra secretly, he can surprise his captors with a powerful Rasengan and break free.
Another plot development could be that Madara actually wants to turn Naruto to his side. He might believe that Naruto, with his strong will and powerful chakra, could be a great asset. So, during the kidnapping, he tries to convince Naruto of his so - called 'righteous' cause, perhaps by showing Naruto some 'truths' about the ninja world that Naruto was previously unaware of.
Naruto might be initially confused. He trusts Tsunade, so being kidnapped by her would be completely unexpected. He would probably start by asking her why she's doing this.
In this fanfiction, Naruto's character development could be seen as a counterpoint to Madara's. Naruto is all about hope, friendship, and protecting the village. Madara has been through a lot of pain and betrayal which led him to a path of destruction. If Naruto is like Madara in this fanfiction, his development might involve a struggle between his own beliefs and the allure of Madara - like power and ruthlessness. However, Naruto would probably still find a way to use any new - found power in a more benevolent way compared to Madara.