The consequences of the first Mass Effect game wrought havoc on Citadel Space, instigating long-overdue changes in many areas humans had previously been excluded from. C-Sec, which had long been a Turian-dominant law enforcement agency, had other species in their ranks, but before Saren attacked the Citadel, it wasn't easy for a human to advance in the ranks. With so many officers lost during the attack, a lot of positions opened up. For the first time since humans joined the galactic races, they were finally given opportunities to advance their careers.
One of the most notable advancements was Captain Armando-Owen Bailey, a no-nonsense, human C-Sec officer who may not have always played by the rules but bent them to make sure the job got done right. In Shepard's first encounter with Bailey after their resurrection, he did everything in his power to help them gain access to the Citadel and important information that aided them in their searches for squadmates and intel that led to the completion of more than one squadmate loyalty mission.
To say Bailey is a hero may seem short-sighted at first glance, but in truth, his unwillingness to compromise on his principles brought a new type of order to C-Sec. Bailey recognized that in order to catch the truly hard and dangerous criminals, he sometimes needed to cooperate with the lesser-thugs to get intel that led to bigger busts and a more stable Citadel environment for everyone.
He showed compassion for duct rats like Mouse, whose knowledge of the underground lead Commander Shepard and Thane closer to his estranged son, Kolyat, during Thane's loyalty mission. He even looked the other way while Thane and Shepard used force to question Elias Kelham -- despite this interfering with his own personal and business arrangements with Kelham -- because he wanted to help them find Thane's son. After taking Kolyat into custody, Bailey was willing to work with Shepard and Thane to bend the rules on getting Kolyat a lesser sentence, despite the attempted murder charges he faced, because he understood that kids make mistakes and taking away their second chances in life will only serve to make them harder criminals in the long run. He drew Kolyat under his wing and put him to work helping out in Zakera Ward, hoping it would get other kids like Mouse off the streets and out of crime.
In the numerous accessible files on Captain Bailey, including Cerberus and Shadow Broker intel, Shepard discovered that he was divorced. His comments about his reason for helping Kolyat suggested that, much like Thane, he was a father who made mistakes. In aiding Thane and Kolyat, it's possible that Bailey himself was acting through them to find the courage to repair the damages he'd done with his own family by putting his military and law-enforcement career first.
In the Mass Effect: Inquisition companion comic, Bailey earned a promotion to Commander of C-Sec in the Citadel Embassies after investigating Executor Pallin under Udina's orders. Needless to say, Bailey wasn't entirely pleased with his promotion, as he'd never been one to sit behind a desk pushing pencils when there was work to be done elsewhere. Still, he used the resources at his disposal to help Shepard on numerous occasions after the Reapers began attacking Earth in Mass Effect 3.
When Cerberus stormed the Citadel in a surprise attack, Bailey was an essential force trying to re-establish order and take back C-Sec headquarters. Despite being wounded in the attack, Bailey did everything in his power to set up a backup network for his fellow officers to launch a counter-attack against Cerberus. He helped Shepard discover that Udina was the traitor and then aided them in reaching the roof before Kai Leng in time to save the Council.
Bailey even showed up during Thane's memorial service during the Citadel DLC to offer his silent support and respect for a Drell he related to and respected, despite knowledge of Thane's career as an assassin. A hero of the Citadel, Commander Bailey proved himself more than worthy of the accolades, though it's almost certain he would brush them off by refusing to let his pride get in the way of doing the work that truly defines him as a man.