9k is a captain in the highly-trained Maximal Command Security Force. His job is to uphold the will of the Maximal Imperium on Cybertron in the name of the Pax Cybertronia. A highly-decorated officer, he prefers to stay in the field with his troops despite his high rank. His skill with energon weapons makes him a dangerous opponent.
After a Predacon defeated three Maximal cops, 9K had a one-to-one combat with him. It seems 9K was defeated, too.