with wild theories that threaten to obscure the facts. He once 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 had performed for someone in witness protection. Castle's 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 had been paid for after her death. Initially portrayed as jocular and immature, such as having a bulletproof vest made up for himself that says "WRITER" rather than "POLICE", Castle's character deepens as the series progresses. In "Sucker Punch", while attempting to catch the killer responsible for the death of Beckett's mother over a decade ago, Castle willingly donates $100,000 of his own money for a fake hit, to lure out the killer. He then offers to terminate his partnership with Beckett after she was forced to shoot the real killer, revealed to be a contract assassin silent about his employer. Beckett rejects the offer on the grounds that Castle makes her hard job more fun. In season 3 "Nikki Heat", Castle is upset when B-movie actress Natalie Rhodes is cast as Nikki, thinking she is not right for the role. When Rhodes comes onto a case to observe Beckett, Castle is further insulted that she has not read the actual book. Rhodes considers him unimportant to the film and Beckett likes having Natalie around. However, as the case goes on, Rhodes begins to copy Beckett's mannerisms and outfits, complete with brunette wig, annoying Beckett while Castle begins to like her more. At one point, Rhodes kisses Castle, making it clear she wants to sleep with him to feel the character more but Castle turns her down, telling Beckett that sleeping with the actress playing the fictional version of her is "way too meta". In "Knockdown", Castle helps Beckett in catching her mother's killer. When Martha points out that he has written 22 books before meeting Beckett but he did not have to go to police station every day, Castle replied by saying that it is not about the books anymore. Castle and Beckett finally kiss as a ploy to distract a guard, although their reactions imply that they both felt something. Since then, despite Beckett's then current relationship with another man, they begin spending increasing amounts of time