On the other hand, Snape might be secretly touched. After all, he has endured a lot of hatred from Harry for years. If Harry's apology is heartfelt, Snape might show a small sign of acceptance, perhaps a slight nod or a less hostile tone in his voice, but still try to maintain his gruff exterior, saying something like 'Well, Potter, don't make me regret this moment of leniency.'
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.'
Snape could also be dismissive. He might think that Harry's apology is too little, too late. He could simply turn his back on Harry and walk away, muttering to himself about how Harry should have known better all along. This reaction would show that Snape is still bitter about the past and not ready to forgive Harry easily.
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.
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.
He could also be secretly amused. Despite his stern exterior, Snape might see a bit of his own unrequited love in their relationship. So, he might give them a stern warning but not be as severe as he usually is.
Snape's reaction could also be one of extreme caution. He would be constantly on guard, worried that Harry might discover some of his secrets or that Voldemort's supporters might target Harry while he's in his care. So he would be very vigilant, but this might also lead to some over - the - top reactions when Harry does something even slightly out of the ordinary. However, over time, this vigilance could turn into a form of care as he gets used to Harry being around.
Snape might be initially shocked. He has his own preconceived notions about Harry, and this revelation could completely change his view. He might struggle to accept it at first, given his traditional and somewhat rigid personality.
Snape would probably be very conflicted. On one hand, he has a long - standing grudge against James Potter, Harry's father. But on the other hand, he loved Harry's mother, Lily. So, he might be cold at first, but then his sense of protecting Lily's son could kick in. He would likely be very strict with Harry, as he is with all his students, but also secretly keep an eye on him to make sure he's safe.
Snape could be very sarcastic and cold at first. He might taunt Harry about finally coming to him for help. However, as he realizes the gravity of the situation, he could start to take it more seriously and actually use his skills and knowledge to help Harry. For example, he might say something like 'Potter, so you've finally realized that you're in over your head and need my help? Well, don't expect me to hold your hand.' But then he would still start to investigate the problem.
In some fanfictions, Snape might awkwardly try to comfort Harry. Given his own complex personality, it wouldn't be an easy or natural gesture for him. He might pat Harry's shoulder stiffly or offer some gruff words of reassurance like 'Pull yourself together, Potter.'
Snape might also keep what he saw to himself at first. Instead of immediately confronting them, he could choose to observe them further. He might be curious about what they were really up to and use his skills as a spy to find out more. This way, he could gather more information before deciding on the best course of action, whether it be punishment or something else entirely.
Snape could be in shock. He might freeze for a moment, unable to believe what is happening. His face would show a mixture of horror and disbelief as he holds Harry's dying body.