Okay, so my last idea was distinctly un-scary, so I'm hoping this one's more in the right direction.
The main idea here is that there's this usually-invisible animal which induces anxiety and fear in its prey (humans) by making creepy, nighttime noises: a tap and scratch at your window, the sound of your doorknob shaking, a far off scream… stuff that'll freak you out if you wake up in the middle of the night to hear it. Once its target is sufficiently scared (heart rate up, adrenaline pumping, mind racing), the animal becomes visible. The target is in the right state of mind to see things he or she wouldn't normally be able to.
Then, when the creature makes eye contact with the person, it teleports to its victim's face, latches on, and induces weird brain wave patters using an electromagnetic field, causing a state of paralyzed fear. After a few minutes of exposure to the EMF, the prey's brain will be nearly-permanently rewired to remain in this state, at which point the animal can safely feed for hours or days at a time.
I feel like the ideas are a bit all over the place, but how does it sound? Has a similar idea been done? Is there enough here to start expanding on it? I think there are probably two parts to this: the hunt and the feeding. They seem a bit disconnected. Any tips?