Snape could initially be skeptical. Given their long - standing enmity, he might not believe that Harry's apology is sincere at first. He might respond with a cold glare or a sarcastic comment, like 'Potter, your apologies are as empty as your head.'
One possible reason could be for misjudging Snape all those years. Harry might have finally realized that Snape was on the good side all along, working as a double agent against Voldemort. This realization could lead to his apology as he understood how much Snape sacrificed and how wrongly he was treated by Harry and others at Hogwarts.
One reason could be that James finally realizes the extent of his bullying. In the original story, James often harassed Snape. In fanfiction, he might come to understand how much pain he caused Snape and feel genuine remorse. Another reason could be that he discovers new information about Snape that makes him see Snape in a different light. For example, he might find out about Snape's love for Lily and how his actions towards Snape affected Lily as well.
In some fanfictions, Snape might see this as an opportunity for his own growth. He might accept the apology gracefully, realizing that holding onto grudges isn't helping him. This could lead to a new relationship between them, where they start to understand and respect each other, or at least tolerate each other's presence.
In a 'Harry apologizes to Parvati' fanfiction, the reason for the apology could be that Harry misjudged Parvati. He thought she was being nosy when she was just concerned about him. He goes to her in the Hogwarts corridors, pulls her aside, and sincerely apologizes. Parvati, being kind - hearted, accepts his apology and they end up becoming better friends, sharing secrets about their families.
In some fanfictions, Hermione might apologize to Harry for being overbearing. Maybe she realizes she's been too pushy with her studies or her plans, and she says sorry for not considering Harry's feelings more. For example, if she's been forcing him to study for exams when he's clearly stressed about Voldemort. It shows her growth as a character.
One possible scenario could be that Harry realizes he misjudged Draco all along. Maybe he discovers that Draco was acting out of fear or family pressure rather than pure malice. For example, Draco might have been forced to take on certain tasks by his Death Eater father, and Harry finally understands this and apologizes for always being so hostile towards him.
Well, often Hermione apologizes to Harry when she realizes she's been too critical. Like when she nitpicks his spellcasting in front of others. She'd then say sorry for embarrassing him. It's a common trope in fanfictions to show her self - awareness and the importance of their friendship.
It often changes for the better. After Harry apologizes, Draco might be initially skeptical. But as they start to interact more, they could become friends or at least develop a mutual respect. For instance, they might start sharing their experiences during the war, which helps them understand each other better.
Another way Snape could comfort Harry is by standing up for him in certain situations. Maybe when other teachers or students are being unfair to Harry, Snape steps in and defends him. This act of protection can be a great source of comfort for Harry, as it shows that someone is on his side even if they have had a rocky relationship in the past.