What is a Big Bad Dummvirate?

You might ask your self what's worse than one Big Bad? Two Big Bads, possibly more, working in intentional collusion with each other. Sometimes they will work together just fine; being all respectful and well, but more often than not there will be rivalries between them, and they will tend to break out into a literal example of a Civil War. Sometimes they are friend other times they are in a romantic relationship what is clear is that both work togeather to complete whatever they want they want to achieve. They are not working attacking one another but instead they are working (sometimes witha silight rivarly) side by side.