Despite only a handful of appearances in Twin Peaks: The Return, the character of Richard Horne has garnered a great deal of speculatio. With the revelation in 'Part 10' that Sylvia Horne is his grandmother, we have to let go of the hope that Richard is the son of Jerry or Ben. That doesn’t leave many options other than that he is the son of Audrey Horne. From what's been seen of him so far, there’s a strong case to be made that he’s the son of Bad Coop, but it isn’t the only case out there.
The first and most obvious theory has Bad Cooper fathering Richard with Audrey. As established in 'Part 7', Cooper’s doppelganger had gone to visit the comatose Audrey in Intensive Care. The implication was that he raped Audrey and she gave birth to Richard (ostensibly while still in the coma) nine months later. Richard’s propensity toward sexual violence and anger is particularly telling, as the entities in the Black Lodge often engage in these acts. This is further driven home by the suggestion that Bad Cooper raped Diane before disappearing 25 years ago.
Richard’s connection to the stranger elements of Twin Peaks -- and with the real Dale Cooper himself -- was established by the Giant who warned the missing agent in 'Part 1': "Remember 430. Richard and Linda. Two birds with one stone." Linda has yet to be seen on-screen, but in 'Part 6', she was described by Mickey as being a veteran who was confined to a wheelchair. Given the reference point of Sheriff Truman’s son being a veteran as well, it’s likely that Linda is a recent vet. The “two birds with one stone line” could indicate that Linda is Richard’s sister, likely his twin.
It should be noted it’s possible that Linda could be the product of Bad Cooper’s assault on Diane, who, as we’ve learned, is undertaking her own agenda. Diane received a lowercase copy of the same text Bad Coop sent to someone else in all caps. Albert mentioned that the text Diane received was sent from Mexico. We know that Bad Coop is still in the North Dakota area and that Phillip Jeffries has spent a great deal of time in South America and around Mexico. It is likely that Diane and Jeffries are working together, and it’s possible that Linda is aiding them in some way.
Richard himself has so far threatened a girl at the Roadhouse with assault, beaten up his grandmother, engaged in vehicular homicide, attempted to murder his kindergarten teacher, and is complicit in a larger conspiracy to smuggle drugs across the Canadian border and into Twin Peaks. The latter enterprise is particularly reminiscent of the national crime syndicate that Bad Coop has been running for the last quarter century. Smaller details also seem to connect the two: Bad Coop and Richard both have a propensity for backhand slaps, chokeholds and for wearing thin jackets with button-down shirts. Twin Peaks hasn’t shied away from symmetry before, but then, it hasn’t shied away from red herrings either.
The relationship between Dale Cooper and Audrey Horne was a major piece of the original series. It was optimistic, naïve and sweet. Given Cooper’s hesitance about her age and the unfixed nature of his job, there was a sense of tragedy to it as well. One of the things fans were most excited to see upon the return of Twin Peaks was some sort of resolution between the two. That we have yet to see Audrey by the halfway point of the new season has been a sticking point and one that is speculated on, often in the same breath as Richard’s parentage. That Bad Coop may have raped the comatose Audrey tarnishes the adorably innocent connection that the real Coop and Audrey shared, which has become nearly sacrosanct in the fandom. Most recently, Dougie/Coop was hyponotized by the red pumps being worn by a passing doctor, similar to the ones Audrey had worn in the pilot episode. This speaks to the depth of Cooper’s emotions for Audrey -- something immutable and unaffected by time and distance.
Much of the sweetness that the new Twin Peaks lacks and the old one had in abundance was the result of the scenes Cooper and Audrey shared. The death of that sweetness by the ugliness of Bad Cooper’s actions is something many fans fear. This has lead to a desperate theory: that John Justice Wheeler -- whom Audrey had sex with shortly before she was in the bank explosion -- is the father of Richard. But there is one other possibility. A member of the Horne family we’ve forgotten about: Donna Hayward.
Toward the end of season 2, Laura’s stalwart friend discovered that her mother had an affair many years ago with Ben Horne. Donna resulted from the affair. It’s possible that Richard is Donna’s son (they have the same eyes), possibly from James. We know James has returned to Twin Peaks and has been strange and quiet since his motorcycle accident. Since Lara Flynn Boyle declined to return as Donna, the story could be that Donna died in the accident (or otherwise skipped town because Richard is a lost cause). Either could explain her absence. Over the 25-year span of time between the two series, maybe Donna had come to accept Ben Horne as her biological father. It would also help to explain (besides his personality) Sylvia’s dislike of Richard (as well as the spiteful way he spat “Grandma!” at her) and her demanding that Ben pay her back for Richard’s burglary. She feels she is owed by Ben who is responsible for Richard in some specific way.
Twin Peaks has often asked the question of nature vs. nurture, often falling somewhere in the middle. While Ben and Jerry Horne have mellowed in their old age, these were the same people who used their department store to groom high school girls into a prostitution ring, attempted to sabotage rivals and had people killed. Ben himself slept with and pimped Laura Palmer, the daughter of his best friend and business partner. The Hornes have been less than stellar citizens, and it wouldn’t be all that surprising to see the rotten apple not falling particularly far from the tree with regard to Richard.
Yes, this theory requires some mental gymnastics, but Twin Peaks has always had complex mysteries with branching red herrings meant to tease out the plot just to surprise the audience.