There are many possible plots. For instance, the sentient armor could develop a sense of self - preservation that goes against Iron Man's heroic nature. It might refuse to engage in extremely dangerous battles, causing a rift between it and Tony. Or the armor could start to have a 'personality split' due to some glitch in its programming. One part of it is still loyal to Tony, while the other part has a more radical view on protecting the world. Additionally, the sentient armor could be abducted by an alien race that wants to study its advanced technology and Iron Man has to rescue it, which could lead to some interesting interactions between the armor and the aliens.
The sentient armor can make Iron Man more cautious. Since the armor has its own thoughts, Tony has to consider its opinions. This forces him to be less impulsive. For example, when the armor warns about the potential consequences of a certain action, Tony might hold back.
One possible plot could be that Spider - Man gets trapped in a high - tech booby trap set by a new villain. Iron Man, using his advanced scanners, locates Spider - Man and uses his repulsor rays to carefully dismantle the trap and free him. Another plot might involve Spider - Man being poisoned by a new type of venom. Iron Man, with his knowledge of biochemistry and technology, creates an antidote in his lab and races against time to administer it to Spider - Man. A third plot could be that Spider - Man is caught in a collapsing building during a battle. Iron Man arrives, uses his super - strength to hold up the building long enough for Spider - Man to escape and then they team up to defeat the villain who caused the building to collapse.
Perhaps there's a plot where Harley's sister has to be protected by Iron Man. She might be in danger because of her relation to Harley or some secrets she holds. And in the process, they form a special bond. Iron Man might use his advanced suits and technology to keep her safe from various threats, like villains who want to use her as a leverage against Harley or Stark Industries.
One possible plot could be that Iron Man is trapped in a dangerous experimental energy field. Spiderman uses his agility and web - shooting ability to create a sort of web - shield around the field, preventing it from expanding and harming others. Then, he figures out a way to disrupt the energy source by using his knowledge of science from school and his own experiences in battles, finally rescuing Iron Man.
Another storyline could involve Naruto having to adapt to the high - tech nature of the armor. He's used to his chakra - based techniques, so learning how to operate the suit's complex systems would be a challenge. Maybe he teams up with Tony Stark (in a crossover sense) who helps him master the armor. And together they face a new threat that requires both ninja skills and Iron Man - style technology to defeat.
One interesting plot could be where Metallo somehow gets an upgrade that can disrupt Iron Man's technology. Then Iron Man has to rely on his wits and basic engineering skills to fight back. Another could be a scenario where Iron Man has to protect a city from Metallo without using his full - powered suit, making it a more challenging fight.
In fanfiction, an Iron Man armor made of Uru could be extremely durable. Uru is the same material as Thor's hammer, so it might be able to withstand powerful attacks that normal Iron Man armors couldn't. It could also potentially have some magical properties, like being able to conduct electricity in a more efficient way or having a natural resistance to certain types of energy. Maybe it would be heavier than the regular armors, which could pose some challenges for Tony Stark in terms of mobility, but he would surely find ways to overcome them with his genius engineering skills.
A plot could involve Iron Man losing his suit's power source. By chance, he stumbles upon a box of Lucky Charms. Through some scientific tinkering and a bit of magic from the Lucky Charms' 'lucky' aspect, he manages to create a new power source for his suit. This new power source gives his suit some unexpected and fun abilities, like being able to fly faster with a rainbow - like trail.
One interesting Iron Man 2 fanfiction could be about an alternate ending where Pepper Potts becomes Iron Woman. She uses Stark's technology in a new way to fight off villains. Another could be a story that focuses on Rhodey's perspective during the events of Iron Man 2, exploring his thoughts and feelings about Tony's erratic behavior. There are also fanfictions that introduce new characters, like a young inventor who teams up with Tony Stark to create an even more advanced suit.
One interesting Iron Man fanfiction could be about him teaming up with a young protege from a small town. The protege has a unique power that Tony discovers and decides to mentor the kid, leading to adventures across different dimensions.