Adult Akilah Theory
Saw someone talk about how Akilah was going to miss the rescue while she is in the cave and I could definitely see this happening with Adult Akilah looking for revenge.
Who would be responsible for her missing out on the rescue due to trying to have visions in the cave? Travis and Lottie.
Which adult survivor died off screen and declared a suicide? Travis and Lottie
I think Akilah made it out way later and had a grudge on Travis and Lottie which she later murders and frames the death as suicide. It’s possibly that she’s not the only one left behind and maybe getting help from other unknown survivors. I could see Melissa being involved and holding a grudge on Shauna for abandoning her.