There's a wealth of RWBY Volume 9 theories and predictions but few fan theories are so common as those surrounding the Summer Maiden. There are multiple candidates for the role and strong indications as to who she might be, but her identity is shrouded in mystery. So, who is the Summer Maiden in RWBY?
Related: Is RWBY: Ice Queendom a Reboot?
About the Maidens
To understand the concept of the four Maidens in RWBY one has to first understand the state of the world of Remnant.
As the name indicates, the Remnant is a remainder of something greater, and that is magic.
As Volume 6 demonstrates, before the gods destroyed the world due to Salem's actions, humans were able to yield magic in a fuller way than anything we've seen in the narrative present. In the recreated Remnant, humans only have a Semblance of magic, rather than magic as such.
The four Maidens are the only ones who are able to fully use magic, making them very formidable opponents.
Who Are the Maidens So Far?
Ozpin had planned for Pyrrha to be the Fall Maiden, but this plan failed when Cinder Fall killed Pyrrha and stole the powers for herself.
The Spring Maiden was thought to be a young ward of Raven, Yang Xiao Long's estranged mother. It was, however, revealed that Raven herself is the Spring Maiden.
Weiss Schnee's elder sister, Winter, was initially supposed to succeed the ageing Winter Maiden, but this did not happen as Penny, who was there at the time of the Winter Maiden's death assumed her powers instead.
Upon her own death, Penny transferred the Winter Maiden powers to Winter Schnee as per the original plan.
Who Is the Summer Maiden?
In the 8 existing RWBY Volumes, the identity of the Summer Maiden remains unconfirmed. Based on hints we have so far, it's possible that Ruby's mom, Summer Rose is (if she's still alive, as some fans believe) or was the Summer Maiden at some point.
This theory, has, of course, been created due to her name. Cinder Fall and Winter Schnee are both named after the season of the Maiden whose powers they hold. This was almost averted with Winter but the powers ultimately shifted back to her.
This, of course, isn't the case with Yang's mom, whose full name is Raven Branwen. But Yang is Ruby's half-sister, so if both sister's mothers were among the Maidens a symbolic connection would be maintained.
On the other hand, it's possible that the show writers gave Ruby's mom the name Summer precisely in order to shift our attention from the real Summer Maiden or to introduce someone surprising and completely unrelated - as it would be a bit too obvious to have another person with a season-inspired name inherit the Maiden powers.
Alternatively, it would be interesting if one of our main characters assumed the powers of the Summer Maiden, as these powers have been reserved for side characters so far. Hopefully, RWBY Volume 9 will finally reveal the answer.