Most times, we try to be nice to people who are rather mean to us.
This can be because we feel pity for them, for instance, a new student comes to school from another school and probably he or she is trolled by the students in the new school maybe 'cause of her looks it something. They fellow might start being rude in response the situation even to people who don't mean no harm. A student in that same class might try to be nice to him/her in other to make him/her confident and handle issues better.