WARNING: The following contains spoilers for Star Trek: Lower Decks Season 2, Episode 3 "We'll Always Have Tom Paris," streaming now on Paramount+.

While Ensign Beckett Mariner is among the U.S.S. Cerritos' junior officers on Star Trek: Lower Decks, it has always been something of a running gag that Mariner is far more experienced than her rank and position within Starfleet would suggest. Well-versed on the different languages and customs from the multitude of alien civilizations that the Federation has encountered over the years, Mariner is something of a quiet veteran amongst her wide-eyed friends who are still relatively naive to the wonders of the galaxy. While on a routine pick-up mission with Tendi, Mariner lets slip that she once served on another Star Trek staple: The Starfleet space station Deep Space Nine.

Located in orbit around the planet Bajor, Deep Space Nine was appropriately the primary setting for the television series Star Trek: Deep Space Nine. Originally constructed and run by the Cardassian Union while they occupied Bajor, Deep Space Nine is staffed by both Federation personnel and the Bajorans. The installation became a strategic focal point during the Dominion War due to its proximity to a wormhole that led to the Gamma Quadrant where the Founders were based, leading the Dominion against the Alpha Quadrant alliance between the Federation, Klingon Empire and Romulan Star Empire. Following the Dominion's defeat, Bajoran officer Kira Nerys took command of the station.

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After Mariner accidentally damages a package she and Tendi are tasked to recover from Qualor II from the Cerritos' Doctor T'Ana, Mariner recommends a repairman she became acquainted with while serving on DS9 some time before being assigned to the Cerritos under her mother Captain Carol Freeman. While Mariner doesn't provide much detail on what exactly she did while serving on DS9, or for how long she was stationed there, she does mention that she once broke one of Worf's belongings and enlisted the repairman to fix it before the famously surly Klingon could notice what had occurred.

Throughout Lower Decks Season 1, Freeman observed that her daughter possessed enough natural talent and professional experience to make her senior officer material if only she took more pride in her job and conducted herself far more seriously. With Mariner having apparently served on DS9, one of the most vital installations in Federation space, this suggests that Mariner's acumen is far more accomplished than she let on to her friends on the Cerritos, though she bristles when Tendi is surprised that her fellow ensign served on anywhere other than the low-priority starship. By the time the two junior officers return to the Cerritos, they both have a greater understanding of each other and their respective backgrounds.

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Just as Lower Decks has seen the return of Star Trek: The Next Generation's Will Riker in a recurring guest appearance, Mariner serving alongside fellow TNG alum Worf leaves the door open for the fan-favorite Klingon Starfleet officer to make his own appearance. Regardless of potential cameos, this revelation of Mariner's past service further underscores that she is not only particularly knowledge about the vast workings of Starfleet, but has served on some of the most important installations that the Federation has to offer. Just as Tendi had to contend with her own past, Mariner's elusive history may come back to similarly haunt her soon.

Star Trek: Lower Decks Season 2 is now streaming on Paramount+, with new episodes premiering every Thursday.

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