In 2387, after one of her employees, Hassan the Undying murdered the Orion Syndicate's head, Raimus, Melani took over Raimus's operations. Starfleet Intelligence believed her to be in control of at least 30% of Orion Syndicate operations, though other Syndicate bosses posed a threat, fearing she might increase her control. It was believed that she was the first Orion in twenty years to have a major position in the Orion Syndicate.
The following year, 2388, Melani D'ian began talks with the Klingon Empire and the Breen Confederacy in order to deal with problems facing the Orions: their dying homeworld in the Rigel system and Starfleet crackdowns on Syndicate operations.
Later, Melani carried out a ruthless purge of so-called 'untrustworthy' Syndicate members and competing leaders, and welded the remaining Orions into a unified force, loyal to her. Orion Syndicate traffic increased markedly under Melani’s control, and Starfleet had a harder time combating their activities.
Melani signed an alliance between the Syndicate and the Klingon Empire in 2394, after four days of negotiations with Klingon Chancellor J'mpok. At these meetings, she posed as a slave girl of Hassan. Subsequently, she moved into an estate on Ter'jas Mor, from which she directed Syndicate operations.
Melani D'ian was noted as being slippery, with a variable idea of 'truth'.