Ideas For My Trailer - Characters

Considering the resources I have, I will only use afew characters. Also, after carrying out research in psychological thrillers I noticed that there are usually only afew main characters. I will probably use younger characters in my trailer as modern thrillers usually involve teenagers (this would also be easier for me as I could use people I know to be in the trailer). I will probably have a classy femme fatale character to link to the Film Noir style, a naive innocent girl to link to the stereotype of thrillers in general and a mysterious male character. I thought it would be interesting to make the two female characters look similar maybe almost identical (by using hair, makeup and costume) to further create a sense of confusion in the thriller. The use of two physically similar characters could link to psychological aspects.