In order to determine if the fanfiction or original work is appropriate for someone, these fiction ratings should help us out.

G = General audiences
AA = All Ages
All ages can read the fanfiction or original work.

PG = Parental Guidance Suggested
Fanfiction or original work may not be read by for younger members.

PG-13 = Parental Guidance Cautioned
Some content may not be suitable for members under 13.

T = Teen
Members over 13 are cautioned when reading inappropriate material.

R = Restricted
M = Mature
Material contains sexual, swearing or violent content. If your ok to read this rating, you have been warned.

NC-17 = No children under 17
No one under the age of 18 may read unless approved by Admins & Moderators - Much more explicit content for this rating.

All information used is credited to:
Motion Picture Association of America film rating system
Critic's Corner