It is pretty clear that when we refer to the unidentified sister of the Winter Queen, we refer to the leader/one of the leaders of the domain of Life (the Dream), since there are the following clues that suggest so: The Winter Queen isn’t fond of her sister, there is this Emerald Dream-Ardenweald antithesis, and then Ysera, a paragon of the Dream and Life, is her “sister’s pet”.
I have already made a topic explaining why it is Eonar who is the sister we are looking for, but let us stick to the new evidence as to why it is not Elune.
Prince Renathal refers to the Stonewright as a “wielder of Elu-” before getting interrupted in the latest PTR storyline, and two quests after we see her slaying dreadlords instantly, using a moon spell, similar to the magic of Ardenweald and Tyrande.
The book “Enemy Infiltration” suggests that beings of Death (either mortal souls or Shadowlands-born beings like the Dreadlords and the Stonewright) have a great distaste for the magic of Life, because of their opposite natures. We haven’t seen any being in the Shadowlands use the light-green druid magic, have we? No. The closest expression of druidism in the Shadowlands is Ardenweald, which is Death and not Life, and therefore there are two possibilities about Elune:
- She is the Winter Queen
- She is a First One, and Denathrius, being an Eternal One, taught the Stonewright how to invoke Elune and create souls for her stoneborn.
SUPER SPOILER: I have been debunked, it is Elune. However, here is another speculation which I have also commented below:
Some of us thought it would be Eonar, because, out of instict, we presumed that her sister would have to be her opposite, both in appearance and in nature- The Winter Queen and Ardenweald stand for, well, winter, Death, and Night, while Eonar and the Emerald Dream (to which Ardenweald is somehow linked) stand for summer, Life, and Day.
That Elune “did not abandon” her and that the powers of both sisters are night themed and not “opposite” or different means that they may have ruled Ardenweald together once. One thing is for sure, Elune was a member of the pantheon of Death, NOT of the equivalent of Life (if it exists), and for some reason, she left.
So where did she go? Although she is the Winter Queen’s sister, she seems far more powerful and linked to several different cosmic forces (she created the Naaru (Light), she protected Eonar in Elunaria (Life/Order), she is worshipped across all the universe, and she has power over Death and spirits (as we can see in many places in Legion). But she can’t be a First One, if she is the sister of an Eternal One, seeing how the First Ones created the Eternal Ones.
The answer is probably this: Xal’atath, a Void being who might well be a dreadlord infiltrator (which is why she was imprisoned) refers to her as an “upstart goddess”. “Upstart” refers to someone who got rich/powerful recently, indicating that she was once weaker and more restricted (like the Winter Queen), that she wasn’t always so powerful.
What if the First Ones called her to their side for doing something very good for the Cosmos (mabye imprisoning the Jailer), and she shares in their power and glory ever since? This would mean that she is still a First One, but without having been born one.