My ds has never been much of a talker, but now he is 13 and a half I have noticed he is even quieter. One word answers, doesn't really initiate conversation, you have to really dig deep to try and get any information about friends, school etc out of him. He's also turned a bit sarcastic and 'attitudey'. As far as I know, all is well at school. He has a nice group of friends and I think they are all OK with each other at the moment. I have no real reason to be worried but when I contrast him to my outgoing, fun, loud 11 year old dd I do worry that he does seem pretty introverted. Would love to hear how your 13 year old boys are at the moment.