the well known Harry Potter cycle
Step 1: thinking Snape is a bad guy
Step 2: thinking Snape is a good guy
Step 3: realising as you mature as a person that Snape was actually a terrible person after all and was an abusive bully who didn’t grown out of this stage even into his late 30s and an obsessive person who thought he was entitled to Lily just because she showed him friendship and no matter how many bias memories of his you are shown you will never see him in any different way
unfortunately some people are still stuck in stage 2