Brenda Chenowith Fisher (1969-2051), played by Rachel Griffiths, is Nate's wife, (formerly his long-time girlfriend). As a child, she was under the scrutiny of Dr Gareth Feinberg and various psychologists who documented her behavior in a book called Charlotte Light and Dark. Being a genius, however, she would study the symptoms of diseases and feign them, to make Charlotte Light and Dark completely inaccurate. Her parents are wealthy psychiatrists while her brother (Billy) is a successful photographer, struggling with bipolar disorder. Brenda spent much of her life care-taking for Billy and has struggled to build her own life outside of Billy's illness. Billy has a strong fixation on Brenda's life and their relationship at times bordered on incest. Brenda's first real love was Trevor, with whom she planned on going to Yale until she chose to stay home after Billy attempted suicide.

Brenda meets Nate Fisher at an airport and they have sex shortly after. The two begin a relationship which is often interrupted by her brother Billy who continues to worm his way into his sister's life. Nate breaks up with Brenda after events cause her sexual addiction to become out of hand. Brenda moves away from Los Angeles and seeks out therapy. She arrives back in L.A. after her father is diagnosed with cancer. She then begins a relationship with a neighbor, Joe, a kind French Horn player who likes to be dominated in bed. After Joe catches Brenda making out with Nate, he ends the relationship and moves out of the house they bought. Brenda gets back together with Nate by whom she becomes pregnant. On the night before their wedding, Brenda suffers a miscarriage which casts a dark pall on her wedding day. Brenda becomes pregnant again and begins an internship as a cognitive therapist. About this time, Nate begins spending a lot of time with Maggie, his stepsister and becomes interested in her Quaker religion. Nate insists that Brenda attend a meeting of Friends ( A Quaker service). Wanting to save her marriage, she complies,only to show up to a meeting and not know that at that moment, Nate and Maggie are at her apartment, having sex. Nate suffers a hemorrage from his AVM and is rushed to the hospital. After appearing as though he is recovering, he breaks up with Brenda, with thoughts of beginning a reationship with Maggie. He dies before this can happen, having never left the hospital. Six weeks later Brenda delivers a premature baby girl named Willa, who eventually becomes healthy enough to go home after spending weeks in the hospital. Years later, Brenda is remarried to a man named Daniel Nathanson, and has a third child, Forrest Nathanson. She dies in 2051 at the age of 82 of natural causes (the audio commentary on the DVD suggests that Billy, still complaining about his failed relationship with Claire, bores Brenda to death).



Billy Chenowith, played by Jeremy Sisto, is Brenda's younger brother, who is a bipolar artist and often has episodes of violent, psychotic behaviour. He has been prescribed psychiatric medication to control his disorder, but frequently causes problems by failing to take them as needed. Billy's episodes have proved chronic, causing critical events in the life of his family. In one example, he allegedly burnt down a section of the family home in 1986. Due to another incident, in which he carves a tattoo out of his back with a box cutter and attempts to do the same to his sister, his family has him committed. (The tattoos were of their favorite fictional characters: Nathaniel and Isabel there was speculation that the two siblings were intimately involved during their childhood, until the episode "Static" showed they hadn't been.) Billy is also an alumnus and teacher at LAC-Arts, where Claire Fisher attends college until late 2004. Billy first meets Claire in 2001 at Brenda's, and they strike up a good friendship until Billy ends it. After being institutionalized, the only person he can talk to is Claire. After he is released he rekindles the relationship, and the two begin dating two years later, briefly living together. After some taunting by old acquaintances that he's not the guy he used to be, and finding himself lacking artistic inspiration, Billy again ceases taking his medication. Soon after, Claire realizes this and breaks it off with him for her own safety. Billy goes back on his medication and asks Claire to forgive him, but she refuses. Billy later helps his sister after Nate dies, until she asks him to leave. However, the two remain close, and Billy is present when Brenda finally passes away.

 From Wikipedia