Question: What was the Watcher's original purpose within the Vault? Is she from a Vault? How long has she been watching things transpire on Pandora?
ooc; She could be. She could be one that gained sentience after her specific Vault was opened and she managed to escape. My only problem is that she’s the only one to exhibit the telekinesis and the ability to talk. That’s not to say any of the others could talk, but it makes me doubt that she’d from a Vault herself. Plus, from all the Vaults we’ve seen so far, the guardian who’s with it usually guarding it gets killed before the vault hunter gets the contents.
Which leads me to my next point. According to the Wiki and possibly the game but it’s been a while since I’ve played through them so bare with me, the Eridian’s were formed on a “class based society based on both leadership and organised warfare” which leads me to believe that she was possibly a high ranking official there? Hence the title of ‘The Watcher’ because only those guarding the Vaults and possibly those with a high enough rank, would gain such titles. Though she does share the same base models as the Guardian Cheru’s but that’s not the point. She has the telekinesis ability, which as far as I’m aware no other Eridian/Guardian type enemy has, so it’s most likely specific to her or at the very least, to high ranking Eridian’s/Guardians. There’s also the chance she has the ability to know about certain events, only certain ones though and more specifically ones about the events revolving around what would happen if a certain Vault was opened (like the Vault of The Destroyer) and what would happen after.
It’s not to say she wouldn’t know about the events surrounding the others but this one was more important. It would explain why we don’t see or hear about her on any of the other vaults and why she didn’t intervene to stop them being opened. She would watch and she would wait until it was necessary to intervene. She knew that she’d have no chance of convincing people to not open them; Jack would probably do it anyway, the Vault Hunters would probably do it anyway and looking like what she does, The Watcher would probably get shot at much in the same way she did at the start of The Pre Sequel. Would you believe an alien if they said that a war was coming if you opened the Vaults? No, you wouldn’t. You’d probably open the Vaults anyway.
She was around at the tail end of the Eridian’s destruction and then went into hiding. If she was part of another Vault, it would explain why she never made an appearance until after The Vault of the Destroyer was opened. There wasn’t much help she could give The Vault of The Sentinel since it was already well protected and the Lost Legion would eventually protect it too. She knew that once Jack got his hands on the contents of the Vault on Elpis, she wouldn’t be able to save the Vault on Pandora either.
So tdlr: Her purpose is to guard to some extent, to watch, wait and intervene when necessary, she could be considered another Guardian of that Vault. Yes, she could be from a different Vault that was opened and managed to escape but I want to doubt it. She’s been on Pandora since a few months after Jack opened the Vault on Elpis.
I rambled and I don’t even know if half of this makes sense.