Do you know that feeling?
In most cases, it starts with you being alone in your room, usually at night. You don't really see or hear anything, but you have a feeling someone might be watching. Even the thought of it makes you tremble a bit. You start with looking behind you, followed by checking the surrounding area. The act ends with you shutting the door or window, or just drawing the curtains.
99.9% of the time, those actions are more than enough, and after a minute or two you already forget that feeling, and just go back to what you were doing before, without any worries whatsoever.
The thing is, that feeling isn't something random. You really get an alert of someone coming. And you really do have a reason for being afraid of it. Luckily for you, your intuition saved you from realizing it before it's too late and you actually face him.
Unfortunately, he is also quite skilled. You see, he knows that you know. He knows that you are feeling quite safe after the feat you just did. At first, it used to annoy him and he used to not be as polite as he is today, but he has learned some new things since. One of his famous attributes is the fact that he doesn't need an open window or an unlocked door.
A few minutes after you've already forgot about it, he'll come. You won't hear him or feel him again, just at the most crucial time. He will just check one thing; the closest gape, crack, or even the wind blowing the curtains off for a brief second every five minutes. Every glimpse he can get, he will. He looks for it, because that's how he'll watch you. You see, he doesn't need a lot of view. Only a small opening, for a great late-night show - the one where you don't even know it's there.
He'll usually just watch you, and trust me, it's better this way. I know, you probably wonder why would he do all those things for such a limited profit, but hey, over the years, he became really, really patient.