Obviously, Harry would be one of the main characters. There might also be his friends like Hermione and Ron, who could either support or be skeptical of his new power.
One interesting concept could be how Harry's control over darkness is manifested. Maybe he can use it to cloak himself in shadows, like a new form of invisibility. Another could be that the darkness he controls has a sentient aspect and he has to negotiate with it.
In 'naruto controls the darkness' fanfiction, it could also be that Naruto is exposed to a dark energy source accidentally. This energy starts to influence his thoughts and actions in negative ways at first. But being Naruto, he doesn't give in. He uses his strong willpower and the positive relationships he has with his friends like Sasuke, Sakura, and others to find a way to control this new dark power. He might have to face some of his own demons from his past, like the loneliness he felt as a child or the times he failed to protect his friends, and use these experiences to better understand and control the darkness within him.
In a 'naruto controls darkness fanfiction', perhaps Naruto initially struggles with this new power. He's a hero associated with light and positive energy, so controlling darkness could be seen as a corruption. But then he realizes he can use it for good, like infiltrating dark organizations by blending in with their dark - themed jutsus.
It could be an ancient evil that has been lurking in the shadows for ages. Maybe a dark spirit that was sealed away long ago and is now breaking free, and Naruto has to control the darkness within himself to fight it.
A powerful dark spirit might be the main antagonist. This spirit could sense Naruto's new ability to control darkness and see him as a threat. So it starts causing chaos in the ninja world, forcing Naruto to use his dark - controlling powers to stop it. The spirit could have the ability to possess other ninjas, making them do its bidding.
One possible plot twist could be that Naruto's control over light and darkness is initially seen as a great power, but it actually comes with a hidden curse. For example, every time he uses it too much, he starts to lose his memories related to his friends and his village. This would add a great deal of internal conflict for Naruto as he has to balance using his power to protect those he loves while also not losing his connection to them.
I'm not entirely sure specifically what 'harry controls ice fanfiction' is about without reading it. But it could potentially be a fan - created story where Harry has the ability to control ice in a fictional universe related to the Harry Potter world or some other fictional setting.
Well, it could be about a fan - created story where Harry has the ability to control blood. Maybe it involves some sort of magic related to blood manipulation that is unique to this fanfiction's concept.
It could be about Harry having the ability to control shadows in a fictional story. Maybe he uses this power for various purposes like solving mysteries or protecting his friends.