Sweet but Psycho Novel

She lives in a world of cupcakes and rainbows, a walking abnormality like everyone believes. Always smiling, never afraid, always looking at the bright and colorful side of things. She's sweet, she's childish, and she has the world wrapped around her slender, blissful fingers. He lives in a world of black and white, the personification of walking death. Feared by many, respected by most. Never smiling, arrogant, and always looking for amusement in the form of blood or sex. He has the world in his tight fist. When two opposite worlds clash by an unexpected incident, one always overpowers the other and with the grumpy, arrogant Mafia King, his black and white world gains a rainbow he did not bargain for.