It could be possible for Eris to serve the last proto-Hive, Taox, to have revenge on her corrupted species for destroying the proto-Hive and her allies, and maybe, [i]just maybe,[/i] Taox will enlist the Guardians to aid her conquest of revenge against the Hive.
-
I haven't found what exactly happened to Taox since she was brought out of stasis by the Ecumene Council and debriefed, but unless she went back into stasis somehow, she would be long dead by the present time in the game. Many do agree that Eris does serve the queen, Mara Sov, though besides being one of Ikora's hidden.