He ran away from his family and accidentally lost his way.
After losing his way, he met Jin and brought him back to Whale Island.
On the way, she told Jin that she was a genius witch but she accidentally lost her way.
He was picked up and brought back by Jin, and grew up with Xiaojie.
They have learned a lot about Xiaojie as both a teacher and a friend, and they have a close brotherly relationship.
PS: You may or may not write about your family, it depends on whether you have forgotten it or don't think about it, or whether you want to write it or don't know how to write it.