|“||The commanders you trained, they're loyal to you. If you were to make a move...||„|
|— Lt. Mancuso, to Admiral Souther|
Lieutenant Mancuso was a senior officer aboard UNN Agatha King during the UN-MCR War. He partook in an ill-fated mutiny attempt against Fleet Admiral Augusto Nguyễn, where he was loyal to Admiral Michael Souther; he was later killed in an attempt to re-take CIC.
Throughout the series
Lieutenant Mancuso is among the senior officers of the Agatha King in the vessel's CIC; both he and Lieutenant Shaffer engage in pleasant conversation with Admiral Souther. Mancuso informs Souther of the King's failing electrical grid, musing on the ship's age and incessant electrical faults. He is present in CIC when the dropship containing Cotyar Ghazi is found amongst the debris of the Guanshiyin, and when Fleet Admiral Augusto Nguyễn orders any survivors to be treated as prisoners of war.
Aboard the King, Nguyễn quickly asserts control over the ship's operations, directing the ship to Io and speaking with the lone survivor from the dropship, Cotyar Ghazi. Ghazi asserts that Avasarala—who was aboard the Guanshiyin and escaped aboard the racing pinnace Razorback—is dead, and further asserts that Undersecretary Sadavir Errinwright is a traitor to Earth. Nguyễn dismisses his comments, and threatens to charge him with treason. Later, Admiral Souther, suspecting Ghazi has more to say, approaches Lieutenant Mancuso, asking about electrical issues. Lieutenant Mancuso, knowing full well that all electrical systems are repaired, understands Souther's subtext, and faults the electrical systems on Decks 2, 3, and 11—where the medbay and Ghazi are located.
Later, when Nguyễn searches for Souther, Mancuso informs him that the Admiral is in his quarters; Nguyễn presses Mancuso for which decks are experiencing electrical issues, and Mancuso informs him of the decks. Nguyễn immediately recognizes that the medbay is on Deck 11, and sets out to confront Souther; Mancuso re-activates the electrical system on Deck 11, subtly notifying Souther that he is in imminent danger of being discovered. Souther leaves the medbay before Nguyễn can confront him; however, he is still later relieved of his command.
In the King's officers' mess, Mancuso and Shaffer consult with Admiral Souther on the recent events surrounding the unexplained diversion to Io and Admiral Nguyễn relieving Souther of command. Mancuso informs Souther that there are many captains in the fleet who are loyal to him, and coyly suggests to Souther the potentiality of a mutiny. Souther immediately shoots him down, refusing to condone discussion of a mutiny.
Mancuso is later present in the King's CIC when the dreadnought is in weapons range of MCRN forces. As Souther establishes that Mars doesn't want a fight, Nguyễn orders the tactical officer to open fire on the Martian warships. Souther, having learned that the war was waged on a false premise via a message from Avasarala, orders Nguyễn's instruction belayed. Mancuso, Shaffer, and several other CIC officers spring to action, drawing weapons on MPs, other officers, and Nguyễn. Souther attempts to order all UNN ships to stand down, but is fatally shot by Nguyễn after his loyalists seize control in CIC. Mancuso is visibly shocked by the death of his superior officer.
Following the destruction of the UNN Jimenez by order of Admiral Nguyễn, Lieutenant Mancuso jumps at MP Hansen, struggling for control of his pistol. Although Shaffer successfully injures Nguyễn, she is shot in return, and Lieutenant Mancuso loses his grapple with the MP; he is shot in the chest and is presumably killed.
|1 "Fight or Flight"||Absent|
|3 "Assured Destruction"||Appears|
|5 "Triple Point"||Appears|
|8 "It Reaches Out"||Absent|
|10 "Dandelion Sky"||Absent|
|11 "Fallen World"||Absent|
|13 "Abaddon's Gate"||Absent|
- The character's name may be a reference to Rear Admiral Bartolomeo Vito "Bart" Mancuso, a character from the film "The Hunt for Red October".
- The character was originally credited on IMDb ahead of actual release; however, that original credit included a misspelling of the character name. The misspelled character name was incorporated into this wiki for two weeks before it was detected. The name is never spoken in the episode of first appearance and the midroll credits don't include the character name so the official source of the character name is the name plate on the character's uniform. The name of the character was eventually spoken in the second and final episode of appearance for the character.