Speaking Dreams by Severna Park
In a retrograde future, where the known galaxy is divided between slavers, a deteriorating empire, and legendary aliens, a young woman with the gift of prescience--Costa--is taken from her home world and sold into service. Unknown to her captors or the woman who reluctantly bys her--Maria LoDire, a diplomat--Costa possesses information that will forever change the balance of galactic power.
As the unavoidable confrontation between three unevenly matched factions unfolds, so, too, does the love of the women for each other. The two of them are thrown into the midst of foretold events, their destinies woven together by a common enemy, their ultimate freedom dependent on trust and fate.