Castle is the son of Martha Rodgers and the father of Alexis Castle, who live with him. Castle's birth name is Richard Alexander Rodgers, but changed it to Richard Edgar Castle when he became a writer (Edgar in honor of Edgar Allan Poe). Fillion describes the family dynamic as unconventional because Castle is "mothered by his... daughter, [then]... turns around and mothers his own mother". As a child, he never knew who his father was- reasoning that he never missed having a father as he never had anything to miss, and it allowed him to imagine that his father could be anyone he wished- and was looked after by a nanny who spent most of her time watching daytime television, with One Life to Live as the inspiration to write his first novel. He also claims to have been kicked out of all of New York's finer academic institutions at least once, and to have picked up speed reading while spending his days as a child in the New York Public Library.
Richard has been married and divorced twice. His first wife was Alexis' mother, Meredith, an impulsive, over-sexed actress. She and Richard occasionally meet for a sexual liaison, causing Richard to refer to her metaphorically as a "deep-fried twinkie" (something that is a treat on occasion, but to have it every day would kill you) when she contemplated moving back to New York. His second wife was Gina Cowell, his publisher and publicity agent, a role she continues after their divorce.
Richard has sole custody of his daughter, Alexis, due to her mother's lifestyle (Although even he acknowledges how slightly disturbing it is that he's the responsible one of Alexis' parents). Due to his own experiences being raised by a nanny, he insisted on raising her himself, made easier by the fact that he works from his large loft apartment, which has been shown in exterior shots to be at 425 Broome Street in SoHo. Alexis is quite mature and responsible compared to her father, and in some sense parents him and herself (such as grounding herself for jumping a subway turnstile). Richard takes great care to look after her well-being, but also behaves like a surrogate sibling in some ways.
Castle also plays regular poker games with fellow authors James Patterson, Stephen J. Cannell and Michael Connelly.
Castle is an author of mystery fiction, with 26 bestsellers under his belt. His first novel, In a Hail of Bullets won the Nom DePlume Society's Tom Straw Award for Mystery Literature. His most popular works comprise a series starring "Derrick Storm,"; Gathering Storm, Unholy Storm, Storm's Last Stand, Storm Season, Storm Rising, Storm Warning, and Storm's Break and in the pilot episode, Castle attends a party for the release of the final book in the Storm series, Storm Fall, in which he kills off his protagonist after becoming bored with the character. He later reads from the novel before a book-signing. Patterson and Cannell both disagree with the decision, with Cannell claiming that he could have crippled Storm instead. Castle's other books include Death of a Prom Queen, Flowers For Your Grave, Hell Hath No Fury, A Skull at Springtime, At Dusk We Die, When It Comes to Slaughter, and A Rose for Everafter. By his own admission, his early works - Death of a Prom Queen, Flowers For Your Grave and Hell Hath No Fury - are of poor quality; he points to Hell Hath No Fury and its story of "angry Wiccans out for blood" as being a low point in his career.
After using his friendship with the Mayor to get partnered with NYPD detective Kate Beckett (under the pretense of conducting research for a new character), Castle plans a new series of novels starring a new detective based on Beckett. Toward the end of the second episode, the name of Beckett's literary alter-ego is revealed to be "Nikki Heat"; in the fourth episode, Beckett takes umbrage at the name- regarding it as a 'stripper name'- and insists that Castle change it, despite his proposing the book titles Summer Heat, Heat Wave, and In Heat. He is later seen writing the second Nikki Heat novel, entitled Naked Heat, which once again displeases Beckett.
He was considered to write three novels revolving around an unnamed British spy- unnamed because Castle and his publisher claimed that saying the name would jinx the deal- that he was apparently a fan of, but rejected the offer when his publisher wanted three more Nikki Heat novels and offered him more money (although it is heavily implied that the fact that such a deal would have terminated his partnership with Beckett may have also contributed to his decision).
In Season 2, episode 6, it is suggested that Castle's interest in death, murder, and the macabre may be the result of witnessing a childhood trauma. When confronted several times about it by Beckett, Castle avoids the question. However, as soon as he tells the story, he admits it's fiction. Later in the episode he admits to his daughter that one of the reasons he writes is to try and understand how criminals could do the things they do.
As a promotion for the show, "Richard Castle's" (ghost-written) book Heat Wave was released in hardcover by Hyperion on 29 September 2009 and debuted at #26 on the New York Times bestseller list. In its 4th week on the list, Heat Wave broke into the top 10 as #6. Heat Wave was released in paperback on July 27, 2010 and debuted at #34 on the New York Times bestseller Paperback Mass-Market list. The novel also features a fictionalized version of the already fictional Richard Castle, aptly named "Jameson Rook," (the first name derived from the Irish whiskey, while the last name comes from the chess piece rook which is also known as the castle) who enters into a partnership with Heat that mirrors Castle's working relationship with Beckett. The second novel Naked Heat was released September 28, 2010 and debuted at #7 on the New York Times Best Seller list.. As with "Heat Wave", ABC released a series of early chapters of Naked Heat online.
In the pilot episode of the eponymous Castle, Castle is consulted by Detective Beckett of the NYPD when two victims are murdered in the style of two deaths portrayed in Castle's novels. Though Beckett wants Castle's access to the case limited, Castle repeatedly defies her instructions in order to see the handiwork of his copycat. Unsatisfied with what he considers a boring resolution to the case, Castle convinces Beckett to continue the investigation, and winds up discovering deeper layers to the crime; while the murders initially appeared to have been committed by the mentally ill client of a social worker who was one of the victims, Castle notes that the murderer didn't duplicate the crimes exactly, eliminating the possibility that he was a deranged fan, realising that the killer was actually the social worker's brother attempting to frame her client so that he could inherit his father's money after his death (His father suffering from terminal cancer). By the end of the pilot, Castle enters into a working relationship with Beckett under the pretense of conducting research for his new series of "Nikki Heat" novels.
This relationship is often strained by Castle's luck in personally encountering the suspects, and sneaking in behind breaching teams even after Beckett has ordered him to remain behind, his attempts to follow them once allowing a suspect a chance to escape (Although in Castle's defence this was merely because his ex-wife called him on his mobile during the stake-out rather than any mistakes on his part). Despite this, Castle's familiarity with numerous obscure subjects has allowed him to continue working with Detective Beckett on what are classified as "unusual" homicides, Castle often being able to provide further assistance and information about the current case due to his wide range of contacts assembled during his writing career- including a CIA agent who was actually willing to break agency protocol by telling Castle and Beckett that their current victim was not a CIA agent despite agency policy being to deny any requests about agent identification- and the research he has carried out during that time.
Although Beckett must often step in to stop him becoming carried away with his theories of what happened when they threaten to obscure the search for the facts, such as when he speculated that a surgeon had been killed for his involvement in an organ-smuggling ring before they discovered that he was wanted for plastic surgery he'd performed for someone in witness protection, his writing career has given him a knack for noting minor details in the situations they investigate, such as when he noted that rent for a victim's apartment would have been paid for after her death. Although initially portrayed as relatively jocular and slightly immature about his role in investigations, such as having a bulletproof vest made up for himself that says 'WRITER' rather than 'POLICE' so he can participate in raids, Castle has demonstrated significant character depth as the series progresses. This was shown most keenly in "Sucker Punch", when, while attempting to catch the killer responsible for the death of Beckett's mother over a decade ago, Castle willingly donated $100 000 of his own money to set up a fake hit to try and lure the killer out so that he could be caught, subsequently offering to terminate his partnership with Beckett after she was forced to shoot the real killer (who was revealed to be a contract assassin who wouldn't disclose the identity of the person who hired him) in order to save his life, although Beckett rejected the offer on the grounds that Castle made her hard job more fun.
In addition to Castle's knowledge of a multitude of topics, he has also demonstrated a high level of marksmanship and personal defensive training, even out shooting Beckett on a range as part of a bet, in which he actually hustled evidence out of her by initially pretending to be a terrible shot; during a confrontation with serial killer Scott Dunn, Castle even managed to shoot his gun out of Dunn's hand before he could shoot at the currently-downed Beckett (Although Castle claimed after Dunn's arrest that he'd actually been aiming for the other man's head).
Castle appears to have multiple skills, including fencing.
In "Tick, Tick, Tick..." he operated a taser, it shows he is at least familiar with basic police weaponry.
Although he has no knowledge of his paternal heritage, Captain Montgomery has speculated that Castle's knack for police work may come from someone in his family despite Castle claiming that the Castle family tree consists of con-artists and circus-folks.
In the second episode of the third season it is revealed that Castle's original name was Richard Alexander Rodgers
According to Fillion, the character's name "Rick Castle" was intended to sound "like you're saying 'Rick Asshole'," and executive producer Andrew W. Marlowe confirmed that "'it's certainly a way when you're yelling his name for it to sound a little bit like...' a profanity." The actor also describes Castle as "a bit of a douche" with "a bit of a Peter Pan syndrome" stemming from a lack of "real male adult role model[s] in his life."
Marlowe explained that he designed Castle's character as one that presents a "storytelling point of view" as a counterpoint to Beckett's evidence-based policework. On casting Fillion to fill the role, Marlowe described Castle as "the right vehicle for the right personality." He also acknowledged the similarity between the Castle/Beckett relationship and the Booth/Brennan relationship of Bones.