In some books in the Isle of the Kings there are stories about a "god of blood" that appeared during the war of the gods but was quickly defeated shortly after coming into existence, as it could consist of a threat to both allies and enemies. What was left of this blood god were just splinters of his power.
According to information from another book on the Isle of the Kings we have this excerpt:
"Searching for a suitable host, the corrupt powers sought out the most powerful creatures they could. They found it in the form of some ancient dragons, whom they lured into an unholy alliance with promises of power and true immortality. They nested in the dragons and with time warped their forms and minds. Promised to become the rulers of all, they became mindless slaves to the powers that inhabited them."
Both the unholy twins and Bakragore look a lot like dragons, so this could be the link between Bakragore and the blood god's splinters.