The Dark Market Syndicate was the name of a group of octopus-like entities whose mind acted as a single consciousness. It served as the de facto government of the Dark Market located in the Delta Quadrant in the 23rd century of an alternate timeline.
In 2262, Eurydice was coerced into working for the Dark Market Syndicate when they took her daughter. She found the Federation starship, USS Enterprise, adrift and moving at sub-light speed. She then spoke with its captain, James T. Kirk via hologram, offering to tow them to a place where they could get dilithium. She then had her ship, the Spectral, tow the Enterprise to the Dark Market.
Eurydice then beamed Capt. Kirk over to the Spectral and then spoke to him about her reasons for helping him and his crew. After docking, Eurydice then took Capt. Kirk and his landing party to meet with a dilithium merchant, Grunthum. After making the deal, Eurydice then took them to meet the Syndicate, to get their blessing.
However, Eurydice betrayed them in order to clear her debts with the Syndicate.
Kirk attempted to peak their interest in peaceful trade relations with the Federation. Though slightly interested the Syndicate had already sold five of his crew and would not release the Enterprise.