wtf is happening I’m so confused plz explain

If I understand correctly, there was something between them at school. MC is a masochist with extremely unhealthy tendencies, and ML is a sadist with even worse tendencies. Neither of them were able to forget each other, apparently because they were perfectly matched in terms of their level of unhealthy minds. And the sadist came back for his masochist. The masochist doesn't have much hope, but that doesn't stop him from being offended.