Decimatus was a JiralhanaeWar Chieftain who lead the Brute and Covenant Remnant defenders of the Jiralhanae colony Ferinus, a remote, continental world on the outskirts of Brute-held territory. Decimatus was widely feared, but barely respected by the various ground troops that he commanded. He was infamously known for mistreating his own pack, often making brash tactical decisions stereotypical of Jiralhanae.
He grew up on the infamously war-torn Doisac and was an able warrior in his youth, excelling at many forms of combat. In particular, he had a fondness for the Type-33 LAAW, also known to the UNSC as a "Fuel Rod Cannon". This was due to his adoration of the smell the rounds emitted after striking a target. However, when put in a command position, disaster struck.