Snape could be quite shocked. Given their history, he never expected such a gesture from Harry. He may be at a loss for words for a moment, and then start to think about how to use the basilisk parts to his advantage, all the while still maintaining his usual sullen exterior.
He might be initially suspicious. Snape is a cautious man, and he may think that Harry has some ulterior motive, like setting him up. But after realizing Harry's sincerity, he could be grudgingly grateful.
Snape might immediately see the potential of the basilisk parts. He is a potions master and very knowledgeable about dark creatures. So, he could start formulating plans in his head right away, while still being a bit flustered by Harry's unexpected kindness. He might try to hide his true feelings, but his actions would show his eagerness to use the parts for something important.
It could be a sign of an unexpected alliance. Maybe Harry realizes that Snape has some hidden motives that are actually for the good, and the basilisk parts are a valuable resource that can help Snape in his own quests, like for potions or in dealing with certain dark magic threats.
Perhaps Harry has a hunch that Snape is involved in some secret project or fight against the dark forces that requires basilisk parts. Harry, being the hero he is, decides to provide Snape with the parts to aid in this unspoken cause. It could also be a sign of Harry's growing maturity and his ability to see beyond their past differences.
Harry could react with anger. He is a strong - willed character. So, he might confront Snape about his hatred. He would demand to know why Snape is treating him this way when they should have a father - son relationship. This could lead to a series of intense arguments between them.
They could also be used in some form of dark magic defense. Snape might use the basilisk parts to create spells or enchantments that can protect Hogwarts from dark creatures or dark wizards. Maybe he could create a magical barrier using the basilisk parts' power that repels any dark magic approaching the school.
Harry might struggle and try to break free. He is a brave character and doesn't like being restrained, so he would likely use his physical strength and magic skills, if possible, to get out of Snape's hold.
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.'
Harry's reaction can be complex. At first, he may show immediate resistance, arguing that he's been wrongly accused. When he realizes that arguing won't get him anywhere, he might become sullen and withdrawn. However, this sullenness is also a sign of his determination not to let them break his spirit. He'll keep thinking of ways to prove his innocence or to show that their punishment is unjust. In some fanfictions, Harry also uses these punishments as a motivation to become better at magic, so that he can one day stand up to Snape and Draco more effectively.
Harry is likely to be angry at first. He has always had a tense relationship with Snape, and this act of spanking would seem unjust and humiliating to him.
Snape might be annoyed at first. He's not exactly the warm - and - fuzzy type, and having a kitten - Harry around could disrupt his usual routine.
Snape would likely be initially suspicious. He's not used to Harry coming to him for help or sharing secrets. But once he realizes the seriousness of what Harry is saying, he might start to see Harry in a new light. He could be grudgingly helpful, still maintaining his cold exterior but secretly starting to feel a bit more protective of Harry.