Before joining the War College, Hasan was the bastard son of a minor nobleman. To cover his indiscretions, his father tried to have him assassinated, but he managed to escape with his life and enough stolen money to pay for his first year of tuition. How he was able to pay for the rest of it is unknown.
He had been told on multiple occasions that he looked very much like his father, so when he was given the chance to change his name at the War College, he chose "Ratface" to insult his father.
He was head of Rat Company, and in his time in charge he drove their score in the rankings even further into the negatives than they had been before. He was about to lose his twelfth consecutive game and forfeit his position as captain when Catherine joined and managed to turn what would have been an easy defeat into a victory against Juniper's First Company. Because of the small part he had played in the victory, he stepped down and appointed Catherine as captain of Rat Company.
Hasan is a generally nice person towards those who don't give him any reason not to be. While he does have a certain degree of pride, he is willing to admit when he is not the best person for a job and let someone more qualified take over.
While he is a mediocre tactician, he has an almost uncanny gift for working with and working around imperial bureaucracy to get supplies. This made him invaluable in his role as supply tribune, especially when people interfered with the Fifteenth Legion's supplies for political reasons.
Before meeting Catherine, Hasan and Aisha Bishara had a romantic relationship. Though they are still generally able to work together, Ratface seems never to have completely gotten over his romantic feelings for Aisha.
Hasan is described as being extremely handsome. He has a slender build, soft features and the medium-dark skin common to Taghreb.