meanager
During the teenage years a person tends to be focused on themselves and their behaviour and mannerisms can be disconcerting. A meanager has not yet learned to put the majority of their ideas and thoughts into a larger perspective and they can be very hurtful to those around them, especially their parents and siblings.
The meanager flopped down on the family couch, grabbed the remote and changed the channel from the current programme that his folks were viewinging without so much as asking if they would like to see the latest MTV programme.