So, I'm starting a new fic for a writing contest and need help choosing a main character. The premise of the story is that the mc is a detective trying to solve a cold case. For the past century, there would be three murders on three consecutive nights every 20 years. All the victims were females around 25 years of age and conventionally beautiful. With another 20 year period coming to an end, the mc is trying to solve the case before anyone else gets murdered. To do this, he visits an old friend from junior high. This friend was once a normal girl, but at the age of sixteen became the vessel for the Oracle of Delphi. He calls on her to help him see into the past and future to solve this cold case. 

I'm really excited for this and have narrowed it down to four candidates, but I'm not sure who to choose. Who do you think?