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The Demetrius is a sewage processing ship in the Fleet. When Kendra Shaw tries to tune in to a Talk Wireless interview with Gaius Baltar, she picks up a transmission from the Adriatic to the Demetrius concerning cargo wasting in Adriatics's holds (Razor).
After Kara Thrace's return, a torn William Adama sends Thrace and a hand-picked crew in the Demetrius on a mission to find Earth, despite Laura Roslin's warnings that Thrace is not to be trusted (Six of One). The Colonial public are told that they are on a survey mission to find food sources, though its disappearance is a matter of considerable media attention (The Ties That Bind). The Demetrius is accompanied by a detachment of five Vipers and a Raptor that are magnetically secured to the ship — four Vipers on the dorsal platform, and a Viper and a Raptor on the ventral one. At least one docking hatch exists on the port side.
After two months, the Demetrius is scheduled to rendezvous with the Fleet or be presumed destroyed. After encountering a Heavy Raider with a copy of Leoben Conoy aboard, however, Thrace decides to abandon the plan. Conoy offers an alliance between the humans and his faction in the Cylon civil war, and Thrace wants to accompany him to his baseship in order to learn what the Cylons know about Earth, but her crew refuses to carry out the order (The Road Less Traveled).
Anders shoots Felix Gaeta in the leg over this and Thrace regains some control over her crew. She decides that it is too dangerous to take the entire ship and risk the lives of everyone on board, so she instead takes the Raptor with Anders, Barolay and Athena as her crew. Agathon remains in charge and decides to wait for her for just over 15 hours: the amount of time they can wait and still make the rendezvous with Galactica. Eventually time runs out and though Agathon waits a minute longer it seems as if Thrace won't return. Just as the ship is about to jump, the Cylon rebels' basestar jumps in and he is contacted by Athena. The Demetrius and the basestar then prepare to jump to Galactica together (Faith).
However, due to their jump drives not being synchronized properly, the basestar arrives at the Fleet alone, causing a panic. With the wireless also damaged, the Fleet believes itself under attack and Galactica responds accordingly. The situation is defused when the Demetrius also returns after spooling up her FTL drives again (Guess What's Coming to Dinner?).
The main quarters area of the ship are small and cramped like that of a submarine. Even the captain's cabin is small and sparse. A common area exists for the crew to assemble and eat their meals.
The ship's bridge is laid out like a small CIC with a table in the center, surrounded by various screens and a tactical plot.
The Demetrius's crew consists of: