He might become more confident. Batman is already a confident character, but with Superman's powers, he'd have a new level of assurance. He could take on any threat without hesitation.
Batman could become more arrogant. The sudden acquisition of such great powers might make him think he's invincible. He might start to look down on others who don't have his abilities. However, deep down, his core values of justice would still be there, and he'd probably realize his mistake eventually.
Naruto's personality would become more brooding. He would be less impulsive and more calculating, like Batman. He might not be as openly friendly as he was before, keeping his thoughts and plans more to himself.
He might become more confident, bordering on overconfident at times. With superpowers, he would have a greater sense of invincibility, which could make him a bit more reckless in his actions compared to his non - superpowered self.
He might become more confident. Having such powerful abilities could make him feel more capable of taking on any challenge. He wouldn't be as timid as he was before.
Well, Batman as a kid in fanfiction would have a very different personality. His determination would still be there, but it would be mixed with a child's innocence. He'd be more likely to make mistakes based on inexperience, but also more willing to forgive and forget. His sense of humor might emerge more, as kids tend to find humor in different things. He could also be more vulnerable, which would make his relationships with other characters more complex. For example, his relationship with Alfred would become more of a father - son dynamic, with Alfred having to be more protective and nurturing.
If Batman had Superman powers in fanfiction, he would be an unstoppable force. He could use his detective skills combined with super strength, flight, and heat vision. Gotham would be a much safer place as he could quickly stop crimes across the city without relying on his gadgets as much. He might even be able to take on more global threats, which would be a huge change from his normal focus on Gotham's underworld.
If Naruto was in a WoW fanfic, his powers would likely be adjusted to fit the game's mechanics. His shadow clones could be more like summoned minions in WoW. They could have different abilities based on the skills he acquires in the WoW world. His ability to sense danger, which is related to his ninja training, could be translated into a form of danger perception in WoW, helping him avoid traps and enemy attacks more effectively.
Batman's personality would be radically different. He would be more power - hungry. Growing up with Darkseid, he would see power as the ultimate goal. He'd be less empathetic and more about achieving dominance, not justice.
If Batman joined the League of Assassins in fanfiction, his personality would likely change quite a bit. He'd probably become more cynical. The League's cut - throat environment and their disregard for human life (to an extent) would make him question his own methods of protecting Gotham. He might also become more secretive from his usual allies, as he'd be involved with a very dangerous and secretive organization. He could develop a more ruthless streak, but still hold onto some of his core values deep down, which would cause internal turmoil.
If Harry Potter were a Superman fan in fanfiction, his personality would likely take on a more optimistic and positive outlook. Superman represents hope and the best of humanity (even though he's not human). Harry, having faced so much darkness in his life, might latch onto this aspect of Superman. He would be more likely to see the good in people and situations. This could change his relationships, as he would be more forgiving and more likely to give people second chances. His new - found optimism could also inspire others around him, like his classmates at Hogwarts, to be more positive in their own lives.
Naruto might become a bit more confident and cocky. Shego is often shown as self - assured, and having her powers could make Naruto feel more powerful. He might start showing off a bit more during battles.