[Honor]

A human girl his approached by a strange old women who proceeds to give her two necklaces. Once with a blue stone and one with a red stone. She tells the girl to wear the blue one at all times and to put the red one around the monsters neck. With that the old women disappeared into the crowd. Meanwhile, there is a vampire considering where he will next hunt...

this is a brief explanation.
Basically the necklace give the girl power to control the vampire that wears the red one, causing him pain if he tries to disobey.
Time period would be modern, setting would be a smaller city I think