Harry's perception might shift from seeing Snape as a simple antagonist to understanding him as a complex and conflicted character. He may come to respect Snape's sacrifices and the difficult position he was in. For example, Snape had to maintain his cover as a Death Eater - like figure in order to gain Voldemort's trust while also protecting Harry. This new understanding could make Harry feel guilty for misjudging Snape for so long.
At first, Harry probably sees Snape as a cruel and unfair teacher. But as he learns the truth, he starts to view Snape as a hero. He realizes that Snape was on his side all along, despite the way he treated him.