You are a succubus.

Lately, you have encountered a few troubles in finding and consuming energy, leaving you now weak and in a verge of collapsing.

As you were stumbling your way from house to house, trying to find a perfect vessel to consume to your fill, until you find a house.

You stopped by the window, and saw a handsome young man sitting on the bed, reading a book in peace and silence. So, you took your chance.