He betrayed his kind and tribe to Illidan and has gained favor of the Naga. Mennu had his tribe locked up in cages and lead the Brokens who joined him. As result of his treachery, he became a corrupted shaman and later sheltered in the Slave Pens and led Illidan;s forces from there. Later on, a group of heroes went to the Slave Pens and slained Mennu. Mennu says he deserves it before being stained, hinting that he had some remorse for betraying his tribe.