Draco was desperate, enraged, and vengeful. A person with these traits would do anything necessary to achieve a certain goal or task, which in this case, was not merely survival, but the destruction of the one threatening him through consumption or appropriation.
As he had once told Vishad, he loved the feeling of taking from others what was rightfully theirs, especially if they didn't like it. No, he had not always been like that, so it was likely another aspect of his personality amended by his bloodline.
Unlike Eva who fought every change, Draco usually went with the flow and accepted them. This led to him being able to manipulate and manifest his bloodline almost as well as Eva did, despite his soulmate having years more training than him.
Their bloodlines had previously been described as nuclear weapons. Why?