Fred Weasley II Headcannons:

When Fred Weasley II went to Hogwarts and started pulling pranks on the teachers, most of them laughed or gave him detention. He never understood why McGonnagal started crying. He then promised to never prank Professor McGonnagal again.

When Fred Weasley II came home and pranked his dad during the holidays, he never understood why his father broke down; he then made a vow never to prank him again.