Katrina Amanda Bennett is a senior associate working at Pearson Specter Litt. Initially working at the District Attorney's Office, she wished to jump into corporate law like Harvey Specter and agreed to help him on a case provided he hire her as a senior associate at Pearson Hardman, where she became Louis Litt's go-to associate.
After Louis resigned from Pearson Specter due to tax evasion, she helped him poach one of the firm's clients that he wished to offer to Robert Zane so that he could gain employment at Rand, Kaldor & Zane, promising to bring her along if she complied. However, Harvey and Jessica Pearson discovered her actions and Jessica fired her on the spot. Knowing that she was just trying to help Louis, Rachel Zane asked her father to hire Katrina as his associate, which he agreed to do so.
She was a tenacious Assistant District Attorney who plays with people's weaknesses to get what she wants within The New York County's District Attorney's Office. When Katrina meets Harvey, whose reputation is "a legend" at the office, she acts tough and says that she wants to take him down. She then reveals to Mike that she was merely trying to impress him because she wants to "make the same career jump Harvey made", which is to a position at Pearson Hardman. She then takes their deal to try to appease Harvey.
Although Harvey had no intention of taking her in initially, he later bribes her with a position if she does not take Mike's information into consideration for the felony hit-and-run case against their client, Liam Colson.
Now a senior associate at Pearson Hardman, Louis Litt confronts her and later tells her that she will be under his tutelage to appease for his loss of an associate, much to Katrina's displeasure. She approaches Donna for advice about him and is told to take Louis on. She and Louis then begin tricking each other regarding a case with a very punitive judge. In the end, after Katrina gets Louis arrested, they call a truce
Having experience from the DA's office, she uses it to pull rank over the other associates, particularly Mike and even Rachel, for being a paralegal. Using shrewd tactics and below the belt moves, she takes credit for Mike's idea by delaying Rachel from helping Mike, and giving it to Harvey before Mike can.
Eventually she learns to work well with the other employees of the firm. After Louis accepts her under his wing, she does her best to learn from him. When Louis' heartbreak prevented him from reviewing the bylaws Jessica wanted an overview of, she tries to take up the workload and even asks Rachel for help, citing her as the best researcher in the firm. Her loyalty proved sincere when Jessica fires her for the deception, and Katrina chose not to reveal Rachel as her co-conspirator. Rachel decided to reveal to Louis what had happened, and Louis returns to work, asking Jessica to re-hire Katrina as loyalty should not be a trait to be punished.
At the end of the season 4 mid season summer finale, she told Louis that the firm needed to drop VersaLife and that he can use that as a client he can bring to Rand, Kaldor & Zane, since he had resigned from Pearson Specter. Jessica initially suspected Mike, seeing as Louis was the one who rehired him as well as Robert Zane being his future father in law, and thought Mike told Louis about VersaLife as a thank you, but eventually she realizes that it really was Katrina due to her loyalty towards Louis. Katrina was forced to resign and Jessica's last words to her was that the firm took back VersaLife so Louis will not be going to Zane, and neither would she.
In the episode, Enough Is Enough Louis had every intention to bring Katrina back to the firm, but sadly was unable to do so. Before she resigned she had settled her differences with Mike and Rachel and formed a good working relationship with them. Rachel then asked her dad to hire her, which she later told Louis to remind him that he had forgotten about her.