Well, it could be through his powerful ninja techniques. Maybe he uses his Sharingan to paralyze Sakura, or perhaps he physically restrains her with his great strength. In fanfictions, there are many creative ways for such a scenario to play out.
Madara could also save Naruto by using his knowledge of the ninja world. Maybe he has some inside information about a plot against Naruto and he intervenes in time to stop it. He might have discovered a secret plan by an enemy group and takes action to keep Naruto out of harm's way. This could involve manipulating events behind the scenes or directly confronting the threat.
Well, in some versions of fanfiction, Naruto might have unlocked a new and super - powerful form of his Sage Mode. This enhanced form could give him the strength and speed necessary to outmaneuver and overpower Madara. Maybe he also gets some unexpected help from allies, like a new jutsu from Kakashi that weakens Madara's defenses just long enough for Naruto to land the final blow.
Well, in some versions, Naruto might use his new and super - powered Sage Mode. He could combine his chakra with the natural energy in a way that gives him an overwhelming boost in strength and speed. This enhanced state could allow him to outmaneuver Madara's attacks and land some really powerful blows that gradually wear Madara down.
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.
Well, in some fanfictions, Sage Madara might use his powerful chakra to create barriers around Sakura, restraining her physically. This could be a way to stop her from using her medical ninjutsu or combat skills against him.
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.
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.
Often, the resemblance could be in terms of the way Naruto stands or moves in these fanfictions. For example, Naruto might adopt a more menacing stance similar to Madara's. Also, his hair could be described in a way that it seems to mimic Madara's wild look, perhaps when he's in the middle of using a powerful jutsu.
In some fanfictions, it could be through a strange and powerful jutsu transfer. Maybe Madara, on the verge of defeat, decides to transfer his Rinnegan power to Naruto for some unforeseen reason, like seeing a new path for the ninja world in Naruto.