Tammi is the ex-wife of Officer Sammy Bryant and the "baby mother" of his child.
In the early seasons, Tammi's naive attitude puts Sammy into a bit of trouble. For example, when Tammi went to the park with her new camera, she asked a gang member if it was okay to have his photo taken; the gang member complied and Sammy eventually saw the picture and recognized the man as a suspect in a previous crime, which infuriated him. Another incident was when a family friend asked her if her dog (who is trained in smelling drugs) to sniff their son's room due to their suspicion that he was using drugs-- the dog ended up smelling marijuana and vandalized a good portion of the room as a result, much to the dismay of the son.
Tammi breaks off the marriage with Sammy because her photography instructor had "fell in love" with her. Sammy at first hates the man but eventually acts civil towards him, realizing that the tensions would make things worse considering that Tammi was carrying his child along with the fact that the art instructor did not have a problem with it.
Tammi is portrayed throughout the series as the stereotypical, naive upper-middle class Caucasian woman. This is demonstrated in season one when Sammy had a young witness named Janila at their house to provide safety, and Tammi's overt skepticism indicated that she was unfamiliar with people of minority backgrounds (Janila is Black).