When Cynthia Bostick decided to take a leap into the world of writing fiction, she turned to her experiences as a psychiatric clinical nurse specialist working with cases of violent behavior. Her debut book, “The Match,” (under pen name Davinia Bostick) was recently self-published last June. A lecturer who teaches online classes in theory and therapeutic communication in the School of Nursing at California State University, Dominguez Hills, Bostick says that readers’ fascination with violent crime is a paradox of repulsion and attraction.