record everything he says, he does, and anything that makes him embarrassed. You can save it on google drive in case he deleted the file on your phone/camera. Spread it to social media if he really does something like that. Or you can threaten him using that video/voice records.
My family is patriarch as f. My brother abuses me a lot yet they alwa...... reply
make a video. dont worry about threatening him- send it to his parents. recommend some sort of help center/therapist. i didnt get a clear age but if hes old enough to be completely aware of his actions at least send the boy off to therapy :p reply
if he were my cousin, I would record him saying that and threaten him to shut the F*CK up his dirty mouth or I am going to send what he did say to his family reply
My dude's been watching way too many serial killer documentaries, lmao. He's quite literally the definiton of ''angsty teenager that has anger issues''. reply