#The Devlin family were all ghosts. every object attached to the loop was part of their ghostly environment

[niko-sasaki-dbd]

Honestly, the ghosts can feel other ghosts theory is very well supported, and I would like to share some proof shown during the season.

In episode 1, Charles clearly felt the other ghost (the WWI soldier, Wilfred) strangling him, he also got his face covered in that black liquid after he took the cursed mask off his face.

If ghosts could be able to play the same rules with other ghosts as they do with the living, Charles could have chosen to simply pass through Wilfred and seize the knife. However, he was unable to do so.

Also, during Episode 3, when that ghost's head exploded, Charles and Edwin were covered with the pieces of his ghostly brain, so I guess, fluids are other things that have their own rules when we talk about ghost-to-ghost interaction.

Sure these are not the prettiest of examples, but they support my point just fine. And I guess, it's good information for when you're writing... All sorts of fanfiction.