Can I help my friend's friend's son?

My friend's friend has a son who is ten years of age. He has a psychotic illness and seems to be under a delusion. He believes he is Harry Potter. I know this as when I speak with him, he says, 'I'm 'Arry Potter - in disguise! I'm in love with Hermione Granger!' Not the actress, the girl from the book. He waves pencils around, pretending they are wands. He wears big gles and constantly ruffles up his hair and has drawn Harry's scar on his head with a red crayon - presumably. My friend's friend worries for his sons future. Apparently at school, he gets ridiculed. He is on medication but this seemingly has not worked. He had been hospitalized once for threatening to stab his teacher. I would like to help my friend's friend as he has been kind to me. But I am not sure what I can do...?