Monica had a strong moral compass, and believed strongly in doing the right thing. She had substantial courage as well: she stood by her controversial asset forfeiture program even when it was wildly unpopular, and also accompanied the Strike Team and uniformed officers on dangerous missions.
Monica's management style was based on a very hands on approach. She left the Barn frequently and even turned the Captain's office in the Barn into a war room. She was wholly committed to her job. She used up vacation days to start observing in Farmington early, and even moved to the district in order to get a better sense for the neighborhood.
She was somewhat naive about politics, and believed that people would do the right thing. Her faith in others paid off sometimes; Vic Mackey largely redeemed her faith in him, by working for her largely on the straight and narrow. Other times, her naivety allowed to get outmaneuvered: City Councilman David Aceveda consistently manipulated and outmaneuvered her, both with the Farmington community and with the Department.
Rawling had a history in Farmington, starting as a patrol officer with partner Rich Nelson. In Back in the Hole, drug kingpin Antwon Mitchell reveals that Rawling and Nelson had an affair, but that Nelson eventually returned to his family. Mitchell claimed that Nelson planted evidence on him that put him in jail for 13 years. When Rawling told Mitchell that Nelson had died of cancer, Mitchell appeared pleased, saying that Nelson has said he would "piss on his grave".
Monica Rawling succeeded David Aceveda as Captain of the Farmington precinct. A morally strong woman, she tried to redeem Vic Mackey and Ronnie Gardocki by involving them in a controversial asset forfeiture program designed to clean up Farmington, by destroying the neighborhood drug trade. The program was extremely unpopular with the local citizens, yet she continued to keep the seizures in place, believing that they did more good than harm. She originally used the same ideology with Vic and the rest of the Strike Team, but after she began to grasp their true nature, she vowed to send them to prison as well. 
When Mitchell murdered an 11 year old girl turned police informant, Rawling was determined to take him down. A video recording of him confessing the murder to Shane Vendrell and also ordering the death of Vic Mackey provided the means to send Mitchell back to jail. However, after finally proving that Mitchell was responsible for ordering the brutal stabbing deaths of two Farmington police officers, Rawling learned that David Aceveda had arranged an immunity deal for the imprisoned drug lord. Learning that the DEA was using Antwon's information to build a case against the Salvadoran drug cartel which had been supplying him with heroin, Captain Rawling ordered Vic and the Strike Team to build a case against the Salvadorans first.
The DEA was enraged that Rawling had forced them to "eat shit," and subsequently threatened to cut off all Federal funding to the LA area unless Rawling was fired. Although the Chief immediately complied, Monica Rawling was allowed to remain at the Barn until Mitchell was delivered to the police station and formally arrested for the Farmington cop killings.
Before she lost her job, Rawling had started an investigation of the Strike Team through an arrangement with Internal Affairs. When they reported Lem's theft of heroin to her, she had been fired and said that it was "someone else's problem now." That someone would be IAD Lieutenant Jon Kavanaugh, the Strike Team's toughest adversary yet.