What Does The Ending Of Blair Witch Really Mean?

And Rustin Parr?

As Lane says to Lisa near the end of the film, the only way to survive is to "do as she says". He's started obeying what the Witch commands him to do, which based on everything we've heard about him, seems to be what also happened to Rustin Parr.

As detailed in the first movie, in the early 1900s Parr killed seven kids in his cabin, now destroyed (a copy of which the Witch uses as part of her book of tricks), which was likely a spiritual link to the earlier, vengeful murders she committed shortly following her death. Afterwards, Parr was released from his curse and stumbled back down to Burkittsville, the last time any went up to the woods before 1996.

A big part of his killings was getting one of the kids to stand in the corner while he brutalised another, which was previously suggested to be because Parr didn't want the other children to watch him, but in the scope of the expanded mythology, is because the other child would die instantaneously looking at the Witch manipulating him. In some ways, he was actually protecting the children, showing some empathy in the face of the self-preserving acts he was doing, making him a more empathetic villain.