Yes, there could be fanfics with that plot. Fanfiction writers like to come up with all sorts of crazy ideas to reimagine the Naruto universe. But it's important to note that this goes completely against the official storyline. Naruto is from the Uzumaki clan and has his own origin story which has no connection to Madara in the original series.
I'm not sure if there is a specific well - known fanfic where Naruto is Madara's son. But in general, the Naruto fandom is huge and there are fanfics that cover every possible and impossible scenario. It would be a very strange and interesting take on the characters, as Madara is an antagonist from a different era in the Naruto story, and Naruto is the main hero. This kind of fanfic would likely involve a lot of creative world - building to make such a relationship believable within the context of the Naruto world.
Chapter 288, ", The Loyal Grenade Launcher Feels Worth It", is the clearest early answer because it turns Platoon's situation into a concrete plot event. A useful checkpoint is the way the scene starts with The battle had reached an incredibly intense state. and follows through with The metal shield in front of it was severely deformed, its stand was....
Chapter 238, ", 'Unique' upgrade sequence unlocked", is the clearest early answer because Gu Hang finally turns buildup into a real advancement. The chapter turns that into something concrete by moving from To remain human, or to ascend to godhood? to Secondly, even if Gu Hang didn't care about "no longer being me," it.... What makes it stick is that it turns power growth's growth into a concrete upgrade step and sets up the next payoff in the power growth storyline linked to Rage Owl Star.
Chapter 233, ", Roll In", is the clearest early answer because it turns Airborne Division's situation into a concrete plot event. A useful checkpoint is the way the scene starts with But despite all this, after fifteen hours, twenty hours, it... and follows through with The closer to the Chaos Array, the easier it was for Gu Hang to bring....
Chapter 159, ", The Starting Point of the Road to Glory", is the clearest early answer because it turns Green Skin's situation into a concrete plot event. The setup is The proximity firepower of the eleven Green Skin Ships made it very..., but the pressure keeps building through And their counterattack seemed weak and feeble..
Chapter 157, ", The Eve of the Star War", is the clearest early answer because the buildup finally cashes out in a real clash. It opens with With three thousand grace points in hand, Gu Hang felt the troubles... and closes on When registering as an Imperial Merchant, the first and third items.... The key payoff is that the danger stops being abstract and the conflict around Rage Owl Star becomes immediate, forcing the surrounding cast to react under pressure.
Chapter 170, ", Mother (Extra 7,000 words)", is the clearest early answer because it turns Rage Owl Star's situation into a concrete plot event. The setup is You see, after he had an idea, the first person he contacted was me,..., but the pressure keeps building through Rage Owl Star always needs a governor, and since he has now made some....
Chapter 192, ", Heavenly Gene", is the clearest early answer because it turns Lacroix's situation into a concrete plot event. The chapter turns that into something concrete by moving from Lacroix and his team members found Chanter Town to be quite a... to Since enemies seemed to be continually moving items out, they could....
Chapter 193, "The Grace of the Kind Father and the Past of Rage Owl Star", is the clearest early answer because it turns Ge Wajia's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Hearing the report, Ge Wajia opened his eyes. and follows through with Was this the victory they wished for?.
Chapter 145, ", I want this big guy!", is the clearest early answer because it turns Green Skins's situation into a concrete plot event. A useful checkpoint is the way the scene starts with The significant increase in productivity brought about an income rise... and follows through with Before now, Gu Hang truly did not know that the Green Skins had such....
Chapter 212, ", Starport Technology", is the clearest early answer because it turns Star Port Technology's situation into a concrete plot event. It opens with For the Wind Falcon and the Lion Tank, the problem wasn't too big. and closes on Of course, it could also be used as a normal laser cannon if one were.... The key payoff is that the chapter closes with "Understood., which gives Star Port Technology a stronger narrative position and pushes the power growth onward.