Fay Li is the PR Rep for Seaboard. While she may work for them, she's also working against them. Like Luisa, she wants the Sixsmith report so she can expose the faults in the Swannekke reactor. Unlike Luisa, she wants the report so she can sell it to oil companies. Luisa wants to expose Seaboard for the safety of California's citizens. Fay Li just wants money.
Just to drive home the point that greed is bad (in case you were still wondering), Fay Li turns to brute force to get the report from Luisa. Her flunkies are instructed to kill Luisa, and Li threatens to murder Luisa's young friend Javier if Luisa causes her any trouble. The only thing that stops her is the bomb Bill Smoke planted in the bank that blows her to smithereens.
Aside from the whole greed and murder thing, Fay Li doesn't seem like that bad of a person. She and Luisa bond over the difficulties of being working women in the 70s. In one memorable story, Li says that she had a man who sexually harassed her transferred not to another department but another state. Since she didn't take the harassment as a compliment, men now call her Mr. Li. Real classy, guys. At first we kind of admired Li's gutsiness, but her later actions pretty much obliterate any respect we had for her.