The Ministry of Magic could turn into an antagonist. If Harry's new cold and strong ways are seen as a threat or too radical, they might try to stop him. This could lead to a conflict between Harry and the wizarding government.
One possible plotline could be that after facing a great betrayal, Harry decides to close himself off emotionally and focus solely on becoming stronger in magic. He might train in isolation, away from his friends, and develop new and powerful spells.
One event could be the loss of a very important person in his life. This loss could shatter his previous beliefs and make him think that being soft and warm - hearted was a weakness. He might also have been exposed to a group of people who took advantage of his kindness. As a result, he decided to toughen up and become cold. Also, perhaps he went through a series of difficult battles where his lack of strength nearly cost him his life, so he trained hard to become strong and in the process, became cold as a defense mechanism.
His relationships would change a great deal. The friends who once knew Harry as a somewhat vulnerable and kind - hearted person would now have to deal with this new, cold - edged strength. Those friends who were closer to him for his softer side might drift away. However, some might see this as a positive change in a way, like they might think he's finally growing up and becoming more self - reliant. But still, there would be a lot of adjusting to do on both sides.
Another one is 'Harry's Transformation into Lord Potter Black'. The plot is centered around how Harry changes as a person after becoming Lord Potter Black. He has to face challenges from those who oppose his new status, as well as dealing with his own internal conflicts. It's a well - written fanfiction that really delves into the concept of identity and power.
Perhaps he is trying to hide his true self. He may have a side of him that he doesn't want others to discover, like some special abilities or a different origin. So, being cold to everyone helps him keep his secrets and avoid getting too close to people who might figure him out.
It could be an evil wizard. There are many powerful and malevolent wizards in the Fairy Tail universe who might target Natsu for some reason and use dark magic to make him cold.
It's possible that Natsu's coldness is a temporary state. He could be under a spell that makes him seem cold, but deep down his true self is still there. As the story progresses, his friends might try to break the spell and bring back the old Natsu. They could search for a cure or a way to reverse the magic, leading to many adventures and challenges along the way.
It could be about loss and the aftermath. When ash becomes cold, it might symbolize the end of something, like a relationship or a great adventure. So, themes of grief and moving on might be common.
One possible plot could be that Naruto experiences a great betrayal, perhaps by someone he deeply trusted in the village. This could make him lose faith in the bonds he once cherished and become cold towards others. He might start to isolate himself and focus only on his own power, believing that relying on others will only lead to more pain.