The song of the sirens would be spoken about with both awe and hated when discussed in the universe in the future. The sirens could use their voices to enrage their allies, causing their bloodlust to soar while also weakening their enemies. Their songs could confuse defenders while allowing attackers to ignore all pain and injury. They could charm individuals to do their bidding, captivate the common person to earn their allegiance or even drown a person in their own doubts and fears, causing them to go crazy. The sirens would be both respected and feared in the many years they fought beside the Asura.
And they would never forget the favor the Asura had shown them by helping them off their dying world and giving them this chance.
Due to their isolation and low, female only population, the sirens would never have developed the means to explore the universe. But with the help of one up and coming warlord, they were given this chance and made full use of it.
