More plot spoilers emerge for "Thor: Ragnarok" and one of the biggest concerns is the location of the Soul Stone.
All of the Infinity Stones have been accounted for: The Power Stone is with the Nova Corps. Doctor Strange revealed the Eye of Agamotto as the Time Stone at Kamar Taj. The Tesseract containing the Space Stone is in Asgard, the Mind Stone is with Vision, the "Aether" or Reality Stone was given to The Collector from Asgard (more on that later) but it is not certain if it's still there.
The only Infinity Stone we have yet to see is the Soul Stone. Is that statement accurate? There are some fan theories which state that we have seen the Soul Stone already.
As proposed by a Comicbook.com reader (h/t Slash Film) Heimdall may already have possession of the Soul Stone all along.
"First, Heimdall is quoted in Thor: The Dark World as saying he can see all the souls in the nine realms. Surely something called the Soul Stone would allow him to do that. Take that into account with the fact that in Thor's vision of the future in 'Avengers: Age of Ultron,' Heimdall is blind. If that future is in a time where Thanos has obtained all the stones, then that could explain his blindness," SF explained.
It was also noted that Heimdall's eyes are orange, similar color to the Soul Stone but that may be a minor detail.
Assuming this theory holds, we may arrive at possible plot spoilers for "Thor: Ragnarok" as suggested in Comicbook.com.
"If Heimdall does have the Soul Stone, Hela could battle (and likely kill) Heimdall to take possession of the stone during 'Thor: Ragnarok.'"
They support the theory: "That scenario makes the most sense, as Thor's vision during 'Avengers: Age of Ultron' features a blind Heimdall telling Thor, 'We are all dead!' before leading into the revelation of the Infinity Stones that are now in play."
If Hela takes possession of the Soul Stone, it could also lead to a more plausible explanation of Thanos' obsession with Lady Death. The personification of Death has yet to be introduced in the Marvel Cinematic Universe. A convenient introduction is that Hela, played by Cate Blanchett, IS Lady Death herself. Instead of Thanos "falling in love" for Lady Death, he could simply be pursuing her for the Soul Stone.
Will these theories hold water? We'll find out when "Thor:Ragnarok" is released in November 3, 2017.