Normal
I'd call (not go over to) the parents first and try to talk it out. They might be just as surprised that their son is bullying others. Bullies often play off themselves as the victims of bullying. Oliver had an issue where he said that a bully was picking on him, but after talking with parents and teachers, we found out, Oliver was indeed the bully. So, we had a talk with him. Approach this cautiously, don't be offensive to the so called bully's parents. If you approach them reasonably, they should respond in kind. JMHO
I'd call (not go over to) the parents first and try to talk it out. They might be just as surprised that their son is bullying others. Bullies often play off themselves as the victims of bullying. Oliver had an issue where he said that a bully was picking on him, but after talking with parents and teachers, we found out, Oliver was indeed the bully. So, we had a talk with him.
Approach this cautiously, don't be offensive to the so called bully's parents. If you approach them reasonably, they should respond in kind. JMHO