One interesting plot development could be Izuku unlocking a new power during the fight. This new power gives him an edge and surprises All for One.
Perhaps in the fanfiction, Izuku teams up with unexpected allies against All for One. This alliance could lead to some really creative battle strategies and interactions.
One interesting plot development could be Izuku using his new control over One for All to quickly master new quirks within it. He might surprise his classmates and teachers with his rapid progress in combat training.
A third plotline could be that Izuku has to fight All for One not just physically, but also in a battle of wits. All for One is a very cunning adversary, and Izuku would need to outsmart him. This could involve Izuku using misdirection, setting traps, and predicting All for One's moves in order to gain the upper hand.
One idea could be Izuku struggling to control the All for One quirk at first. He might accidentally absorb quirks he doesn't want, leading to chaos. For example, he absorbs a quirk that makes him grow extra limbs and has to figure out how to hide it. Another could be that villains target him more, thinking he'll be easy to corrupt with such a powerful quirk.
One interesting izuku all for one fanfiction could be where Izuku uses the All for One power in unexpected ways to save his friends. For example, he might use it to transfer quirks temporarily to those in need during a battle, creating unique and exciting fight scenes.
One interesting story could be about Izuku exploring new powers of One For All in a different dimension. He might face challenges that test his limits and how he uses the power in unique ways.
One interesting fanfiction could be where Izuku uses the combination of All for One and One for All in unique ways to defeat powerful villains. He might use All for One to take away the quirks of enemies and then use One for All to enhance his physical abilities to an even greater extent than normal.
There could be some original characters created by the fanfiction writer. For example, a mysterious mentor figure who has been secretly training Izuku in a special technique that he can use against All for One. This mentor could have their own backstory and motives that are intertwined with the main plot of the fight.
One possible plot could be that Izuku, under All for One's influence, has a completely different view of hero society. He might be trained in unique and perhaps unethical ways, leading to a conflict within himself as he tries to figure out his own identity and what it means to be a 'hero' or a 'villain'.
Izuku could develop more confidence in his personal life. Since he's married to Momo, who is intelligent and strong, he might learn to rely on her more, not just in battles but also in decision - making. For example, when it comes to handling their finances or choosing a new place to live.
One idea could be All Might discovers baby Izuku has a unique quirk manifestation at a very young age and decides to secretly train him from then. Another could be a story where baby Izuku is in some sort of danger and All Might has to protect him while also hiding his identity from the public. Maybe there's a fanfic where All Might time - travels and meets baby Izuku in the past, and tries to change his future for the better.