Lost executive producer Damon Lindelof confirmed in an interview that Lapidus would be a series regular for the show's sixth and final season.

He is first encountered in The Bahamas, ringing the NTSB to state that the body of the pilot of Flight 815 shown on the sea bed, on the Television news, is not who it is claimed to be.

[2] Frank is later recruited as a pilot on behalf of Charles Widmore (Alan Dale), who is chartering a freighter destined for the island upon which Flight 815 crashed.

His team—consisting of Daniel Faraday (Jeremy Davies), Charlotte Lewis (Rebecca Mader) and Miles Straume (Ken Leung)—parachute to safety, and Frank is able to land the helicopter without incurring significant damage.

[2] Lapidus identifies Juliet Burke (Elizabeth Mitchell) as a "local" and in response to the return of Charlotte, who was being held hostage by John Locke (Terry O'Quinn), flies Desmond Hume (Henry Ian Cusick) and Sayid Jarrah (Naveen Andrews) to the freighter.

[4] Later, Frank disagrees with the actions of fellow freighter passenger Martin Keamy (Kevin Durand), a mercenary hired to capture island inhabitant Benjamin Linus (Michael Emerson).

When Keamy murders the freighter's captain (Grant Bowler) in a display of power, he is forced to comply, but is able to secretly transfer a satellite phone to the survivors as a warning.

Due to a lack of fuel, the group—consisting of Lapidus, Sayid, Desmond, Jack Shephard (Matthew Fox), Hugo Reyes (Jorge Garcia), Kate Austen (Evangeline Lilly), Sun-Hwa Kwon (Yunjin Kim) and Aaron Littleton—crash into the ocean, where they take to a lifeboat and are later rescued by the Searcher, a ship belonging to Desmond's girlfriend Penelope Widmore (Sonya Walger).

[9] Sun is determined to remain with Locke and find her husband Jin-Soo Kwon (Daniel Dae Kim), so Frank parts from her, returning to Hydra Island intent on repairing the jet radio to call for help.

[10] Frank later regains consciousness in an outrigger, being transported back to the main island by Ilana, Bram (Brad William Henke) and three other Flight 316 survivors.

[18] Cuse had enjoyed Fahey's roles in The Lawnmower Man and The Marshal, and he and Lindelof commended his "intense eyes", stating that "he has exactly the right sensibilities" for the part.

Lindelof and Cuse felt that the beard worked with Lapidus' character,[22] and allowed Fahey to keep it for the role, with the requirement he shave it back to a more manageable length.

[8] Fahey praised the way the character was developed to suit him, explaining that upon meeting with Lindelof and Cuse, rather than discussing the show with him, they were more interested in him personally and his experiences, going on to incorporate elements of himself into Lapidus.

"[24] Fahey was not given an overarching overview of his character, nor were any of the other new freighter folk, which he found exciting, creating a level of intrigue amongst the cast and crew as well as fans.

[23] However, following their introduction in "Confirmed Dead", the four characters were well received, with Paige Albiniak of the New York Post citing them as a reason behind the show's improved ratings.

[29] Erin Martell of AOL's TV Squad wrote that within one episode Fahey had already won her over,[30] and called Frank her favorite new Lost character.

[31] IGN's Chris Carabott described Frank, as well as the other new characters from the freighter, as "great" and "exciting", writing that: "Fahey's Lapidus has exceptional screen presence that even overshadows the regular cast members to an extent.

"[32] TV Guide's Bruce Fretts praised the casting of the freighter folk, noting that Fahey had been a personal favourite of his since his appearance in The Marshall.

He deemed the group all stronger actors than former Lost stars Michelle Rodriguez, Rodrigo Santoro, Maggie Grace and Ian Somerhalder, and expressed hope that they would remain on the show longer.

[33] Jeff Jensen from Entertainment Weekly called the new characters "fascinating" and wrote that they "totally worked for me, while their intriguing backstories left me jonesing for more.

"[27] Peter Mucha of The Philadelphia Inquirer deemed Frank's flashback "mind-bending",[34] and Oscar Dahl of BuddyTV called "Confirmed Dead" the "perfect introduction" to the new characters, writing that he could not wait to find out more about them.

He wrote that he was amazed by the economy and precision with which the new characters were introduced because "Each got just one flashback and a little time on the island, and yet by the end of the episode, I felt I had a true handle on what they were like as individuals.

"[39] Following the episode "Something Nice Back Home", TV Guide's Trish Wethman noted that she was intrigued by Lapidus' "seemingly heroic antics" in saving a group of the survivors from Keamy and his men, though overall was confused by the motivations of the freighter folk.