I daydream about pain & blood?

You have a chemical imbalance & that's not all. If you have low levels of dopamine (a feel good hormone) you might compensate by causing yourself pain, which your body deals with by releasing endorphins (brain chemicals known as neurotransmitters that fight pain & stress). The endorphins help you temporarily feel good. Eating certain foods can also cause you to release endorphins. Cutting is your way of trying to feel better. I think your preoccupation with blood may actually be your way of expressing that you feel wounded. Maybe you don't know how to say it, who to tell or think that anyone cares. Seeing people bleeding could also be a symptom of anger that you don't know how to properly express. I'm glad you don't cut but you could also try painting to show how you feel, drawing or writing a poem that allows you to creatively express emotions in a positive way. Find productive ways to feel good doing things you like instead of involving pain & blood.