Nah I definitely think Mara Sov is Taox or Savathun

weren't they both they both the same species as oryx, although i suppose savathun would have darkness powers so she could transform herself or something although if that were the case she would already have tried to attack earth since she would want to beat oryx to the traveller

Taox actually wanted Oryx and his sister's dead before they even made a pact with the worm gods. Also Savathun confronted Oryx many times, saying that she thought that what they were doing might not be right. Also Savathun desired to be a queen and a mother since before they became gods. Savathun also had a coven, when Oryx and Xivu Arath didn't. Mara Sov also has a coven. In the Gift of Mast card in the Book of Sorrows, Savathun acquired a 'secret purpose' before telling Oryx and Xivu that they should part ways. I'm thinking this purpose might have had something to do with the Awoken/ becoming an immortal mother and not needing her worm. When you consider the HoW grimoire, and how it continuously hints that Eris and Mara are kind of working together not necessarily against the tower, but in secret, it starts becoming very interesting. Especially because Mara Sov and the guardians were technically enemies before our guardian is resurrected. Basically I'm thinking Eris and Mara are Taox and Savathun. But it's all speculation. Edit: I'm thinking Mara wants the Traveler for the Awoken, not to destroy it as Oryx wanted to. This would give her a reason to fight Oryx, even if she knew her fleet would be defeated. If she did die in the fight, she would still live in her throne realm as well. But I have a feeling that there's a reason Bungie has been ambiguous about her whereabouts.

that sounds like a good theory as well, although taox never recieved a worm and its never explicitly stated that she got powers from the light and if she was the same species as savathun then she would be long dead as they only live for 10 years (although that could be 10 years on their homeworld so it could be argued that 10 years hasn't passed for them yet though i doubt a planet could take hundreds of thousands of years to orbit a star) plus they still wouldn't look like the awoken unless savathun used space magic to hide their true forms but then the eris we know would have to be a replacement of the real eris that went into the abyss since we know eris used to be a guardian and her ghost would probably notice if she weren't a real awoken

Well I can't remember which book, but a direct quote from Taox is "I'm a mother, we live long..." and Taox reappears to challenge them after Oryx and sisters become hive gods. This is after the mention of Oryx destroying multiple worlds. It is implied that Mothers are nearly immortal from the start, that is why Savathun desired to be one. She was considered to be unfit to rule the Krill or the Hive because she showed compassion through wanting to raise her own coven. The Awoken is pure speculation on my part, but to me it doesn't seem like coincidence that Mara Sov still looks like a teenager when she was part of the Twilight Gap, something like 40 years before our Guardian was resurrected. Eris lost her ghost in the Hellmouth and she spent years hiding in darkness from the Hive. So to me literally anything could have happened. When she used a Hive incantation to warp us out of Crotas throne realm she conveniently said it was one of Toland's tricks, but our ghost read Toland's journal and we heard no mention of Toland mastering Hive space magic. I'm thinking instead of Eris being a replacement she rather joined with Taox and became how she is now. Again, there's no proof to a lot of our theory (cooked up with another user in another topic) but I'm convinced.