My son is 11 and his temperament is and has always been so pleasant, however, that by far isn't saying all boys are like that.
At age nine they are really going through a lot of changes, they are no longer a "little" boy and not yet a young man. They sometimes get a little corky with their parents because you can no longer tell them things just for the sake of quieting them down, and some may even argue with you because they have to absolutely know things, so they will sometimes give you a run for your money with information. If you know what I mean.
The drug talk has already begun with my son, because frankly, you have to prepare them anymore at an early age because there is so many ways drugs can be passed onto children in such unique ways that they may very well think it is just candy or the like. It is truly scary!
The sex talk just began here recently because he is in 5th grade now and they just had the big sex education class, so we wanted him to be comfortable about attending the class beforehand. So then if there was something that perhaps he didn't understand he could come talk to us about it.