Betrayal
Lena fights through the journey of "The Shimmer" to ultimately destroy it. Her fight is a symbol of her desperate need to make up for her betrayal to her husband; while he was away in "The Shimmer" she had an affair with another man, though she believed that Kane was still alive.
Ventress
Ventress becomes part of the entity that is taking over the planet at the end of the film. This is a symbol of her need to cling to life, as she is desperate to live in any form she can, even if it is in "The Shimmer" rather than meet her death on earth.
Kane
Kane not knowing who he is at the end of the film though Lena knows it isn't him is a symbol of a soldier who has seen great peril in war. Soldiers such as these have returned home with the shells of who they are, but inside they are uncertain as to their identities after their experience.
Flower Girl
Josie walks away from Lena and becomes a flower person in "The Shimmer". This is a symbol that she no longer wishes to fight it or attempt to understand it; she simply is willing to let it overtake her before she becomes a monster, as she believes Cass did.
Cry
The mutated bear uses a cry it mimicked from Cass as she was dying. The horrifying sound is a symbol of Cass having died a gruesome death, which is used against her friends in order to feed the blood thirsty bear.
