So my three year old goes to his dads house about once a month/certain holliday's and usually stays 3 to 4 days. There has never been any issues arise until these last few months. Lately when my son gets home he becomes very aggressive towards his baby brother and other young children. I dont know what is causing this. I talked to his dad and he admitted to play wrestling and watching cartoons with some violence. Due to the growing severity of the situation we agreed no more play wrestling or anything showing violence in hopes this behavior would go away. He recently returned from his dads house and his behavior is the worst iv seen yet(he attacked his brother and scratched his face up while playing together). However after about two days he returns to his happy cheerful self. He even goes out his way to help his brother and seems to be a normal caring child. I'm so confused why he completely changes when he comes back but after a few days hes back to normal. Has anyone seen anything like this before?!