I believe that most role-plays, particularly public group role-plays, do not require a rating higher than TV 14/PG 13 (am I setting this as a hard limit? No. Just a reference point), regardless of the characters' ages. That is why the term "fade to black" exists. Yes, a character can engage in sexual situations or situations involving drugs and alcohol at any age. Minors in high school regularly participate in such activities, but does it need to be explicitly written? No. It can be referenced without going into fine detail about the setting/scene/situation.