How has researching stock characters helped in planning my own characters?

How has researching stock character helped in planning my own characters?

Researching stock characters has enabled me to gain some ideas about the characters that I would like to show during my Horror film trailer. The stock character that interested me the most was Pandora as I think the idea of a character being presented as innocent and pure but actually either being the killer or helping the killer is a really interesting idea as I believe it will shock the audience. In addition to this, a Pandora character also creates a more sinister killer as it is someone who would never be thought of as a killer until they reveal themselves. In addition to this, I also would like to include The Wanderer as a character as their constant wandering creates tension for the audience as they never know if the killer will be found or if the killer will find them. However, I do not think I will use the Jock, Popular Girl or Pervert as I believe these characters are just used to be killed and do not create much sympathy for the audience as it is seen as inevitable. 

The Orphan Trailer (Example of a Pandora character) 

This is an example of a Pandora character in a Horror film that I believe creates a truly terrifying killer, as unless she reveals her true self to you, she seems completely normal.