They could try to understand his situation. By getting to the root of what makes him cold, like finding out about his past traumas or current pressures, they can then address those issues specifically to help him warm up.
Sharing their own vulnerabilities might also work. If the other characters show Harry that they too have their own insecurities and problems, he might feel more connected to them and start to drop his cold facade. For instance, if a character tells Harry about a time they were betrayed and how they overcame it, Harry might see that he's not alone in his experiences and become less cold.
One way could be through persistent kindness. If they keep showing him genuine care and kindness without expecting anything in return, over time, he might start to open up.
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.
A cold calculating Harry Potter in fanfiction often makes decisions based on pure logic and self - interest. This changes the plot because he may not be as quick to sacrifice himself for others. For instance, when it comes to the Horcruxes. In the original, Harry was quite selfless in his pursuit. But in a 'cold calculating' version, he might weigh the risks more carefully. He could try to find ways to destroy the Horcruxes without putting himself in too much danger. This alteration in his character would then ripple through the entire plot, affecting how other characters interact with him and the overall flow of the story.
Cold emotionless characters can change the plot by making different decisions. For example, in a fight, they might not be swayed by emotions like loyalty or fear, so they could choose a more practical but unexpected way to deal with the enemy. This can lead to new alliances or enemies forming.
In cold blood Harry Potter fanfics, Harry's personality might become more cynical. Instead of his usual hopeful and somewhat naive self, he could be distrustful of others. For example, he might suspect his friends of having ulterior motives more often.
It could be that his new 'godlike' power has isolated him. People might be either in awe or afraid of him, and he may feel that he can't be close to others as before. So he acts coldly as a defense mechanism.
It could be due to a spell. There are many dark spells in the wizarding world that might cause a person to feel cold. For example, some curses can drain the warmth from a body. If Harry was targeted by such a spell, he would be cold. Also, it might be related to his emotional state. If he was feeling lonely or scared, it could make him feel cold inside, just like when people are in a bad mood in real life, they might feel colder than usual.
Well, it can change the plot a great deal. For example, if Harry is a cold blooded reptile, his physical abilities and limitations are different. He might need to sunbathe to get energy, which could add a new layer of difficulty when he's on a quest. Also, his social interactions would be affected as people might be afraid or intrigued by his new form.
I recommend 'The Cold - Hearted Harry'. It's a short but engaging fanfiction. Harry in this is cold because he has been betrayed too many times. It has a unique plot where Harry has to work with his enemies while still maintaining his cold exterior.
Cold emotionless Harry fanfictions often explore the idea of how much the character has been through to become this way. In many of these stories, it could be because of the loss of his loved ones or the constant battle against the dark forces. They usually have a theme of redemption or a slow thawing of his emotions as the story progresses. For example, in 'Frozen Hearts', Hermione tries to break through Harry's cold facade, which leads to some really heart - warming moments.
One great 'Harry Cold' fanfiction is 'The Adventures of Harry Cold'. It has an interesting plot where Harry Cold discovers a hidden magical world within the normal wizarding world. The characters are well - developed, and the writing style is engaging.