"I'm afraid, Darla, and worse, I think it's Arthur I'm afraid of. Or what's left of him."
I've got a theory. I think the implication here is either that 1. Martin is afraid of what remains of Jon, or 2. what remains of all three of them is something to be feared, malevolent in nature now regardless of who they were in life.
I think Sam is going to be sympathetic to Jon and help him escape from the computer, and the fans will cheer...and then this will turn out to be a very bad thing, bc Jon is not fully Jon anymore.