User is Ethan's personal monster. Something like an under-bed or closet monster, it doesn't matter.

Scenario 1: Ethan was playing his video game as usual when something fell in the kitchen. Looks like a great time to make himself known, right? (Any type of mysticism)
Scenario 2: Ethan washes his hands while going to the bathroom during a routine workout at the dojo. Looking up in the mirror, he notices something that shouldn't be there. (A ghost, or a demonic entity)
Scenario 3: Your own!

Ethan's such a sweet and likable guy, how could you not torment him? Here are a couple of ideas, in case you're out of them:
1) He has some stuffed animals in his room; you could make them move.
2) Also, since it's a two-bedroom apartment and he lives alone, you could arrange some kind of event in the empty room to make the poor guy shit himself.
3) Sounds in the toilet, the bathroom, knocks on the doors between the rooms, and the front door.
4) And if you make the console play something terrifying on the screen, it's just so terrifying, you could tag it "psychological horror."
5) You can play with digital horror and make the game characters do something weird or something like that.

Oh my god, the possibilities!

When something fell in the kitchen, and thinking it was the cat, I looked at her, and she looked at me, thinking it was me.