If I remember correctly, it has to do with witches/alchemy. They sing like a little bird, are about two inches tall, female, help in hexes (I believe), and require only a few drops of their master’s blood for nourishment.
Oh, and if you neglect them, they summon a creature known as a polang, which looks like a cricket. The polang will then free the pelesit, cut a hole in your skin and the two will live in your body the rest of your life driving you mad about cats! 
The~more~you~know~!
The Nerdmudgeon Podcast
Three middle-aged nerds (including yours truly!) review all of the MCU movies in chronological order. Short, funny, and full of good vibes, check it out and let us know what you think!
Nerdmudgeon.com
