Another example of a teenager pushing the boundaries! Gotta put a stop to it any way that works. Personally I would continue to just pull him off calmly andf firmly if he doesn't obey the "off" command but if you are worried he may bite you you might want to re think the letting him sleep in your "den" until he can learn some manners. He just needs to learn a bit of respect, trouble is if he learns that by snapping at you you back off it will only make him more powerful. Maybe a baby gate on the bedroom door so he knows its your and your oh's space not his.