I get this question from my kids A LOT but it's NOT blood! Commercially processed chickens have blood drained before being cut, so there's almost no chance of this. The pink discoloration is mostly water and a protein called myoglobin which carries oxygen through the muscles. Purple discoloration in your chicken is a result of myoglobin and purple marrow in the bones. These colors don't really fade as the meat is cooked, and if your chicken reaches 165F, it's perfectly fine to eat!