How do Koreans view North Korean residents?

Recently, as I became interested in Korean culture and started reading about Korean history, I find myself thinking a lot about how Korea, once a single country, became divided into two. So nowadays, I am curious about how South Koreans view North Korean residents. Seeing the concept of 'one nation' fading away as generations pass is both interesting and somewhat sad. Meeting people in areas like Gangnam or Hongdae in Seoul, I feel like I could hear various opinions. I really want to know how Koreans actually feel about this issue. If anyone has any related experiences or opinions, could you please share them?