User blog comment:KaiserLos24/Mystery of the Shadow Isles (Summary)/@comment-5077844-20141101112803/@comment-24073465-20141101194610

From what it looks, the 'black mist' seems to be made of tormented, vengeful souls or something, given how in the video, the souls/ghosts/whatever seemed to be PART of the mist, rather than hiding within it....

Thus the using of pronouns of multiple people might be because of possession of the black mist or something, which leads to a "I am legion for we are many" kind of thing...in fact, that might mean that Kallista is a gathering of tormented souls ala Thresh's lantern....only difference is all of the souls in her being of common purpose i.e. vengance against betrayal, while his is more of a 'dominant personality wins out and tortures the other souls'.....