Polyamory is difficult to define, as it is fairly new to popular Western culture. The entire Fisher family engages in different forms of polyamory during the run of the series. The fact that when polyamory is presented plainly in the funeral home, the Fishers seem unable to relate. A few of their own polyamorous storylines began in this episode as well.
It is unknown whether or not the deceased Nathaniel Fisher practiced any form of polyamory. His wife Ruth Fisher (Frances Conroy), however, had the taste for multiple partners. Ruth had an affair with Hiram (Ed Begley Jr.) before Nathaniel’s death, as she yearned for more love in her life. Ruth’s polyamorous storyline evolves after she marries George (James Cromwell), but still has Arthur (Rainn Wilson) living in the house. Jealousy builds from Arthur, who eventually leaves the house because there is no more love left for him.
Nate (Peter Krause) may be a wanderer when it comes to love. Both he and Brenda (Rachel Griffiths) have long-standing issues with fidelity. Nate is described by Brenda as having issues with commitment. Brenda is described by her boyfriend Joe (Justin Theroux) as being addicted to betrayal. In practice, however, both only seek others when they are in emotional crisis. During Season 3, Nate is married to Lisa (Lili Taylor) who had an ongoing affair with her brother-in-law. Could Lisa have survived if Nate, Brenda and Lisa formed a triad?
David (Michael C. Hall) and Keith (Matthew St. Patrick) represent the truest form of polyamory on the show. From time to time they have open relationship, and share paintball aficionado Sarge (Josh Stamberg). They never actively invite anyone else into their relationship, though David did seek emotional support from Sarge (that drove him away).
Claire’s (Lauren Ambrose) polyamorous storyline is embedded in the college experience. Claire moves between heterosexual and homosexual (unsuccessfully) experiences. Her group of friends function vaguely as a loose pod: everyone seems to have a chance to trade partners. The band of poly friends includes Russell (Ben Foster), Anita (Sprague Grayden), Jimmy (Peter Facinelli) and Edie (Mena Suvari).
Polyamory did not become a main focus for any character in Six Feet Under. The way in which the “monogamous” characters in Six Feet Under dealt with their relationships begs the question: How many monogamous people are on the cusp of polyamory?