Well, you have faeries who gain essence from scaring people. Then someone figures out how to do a role change and they change themselves into faeries who gain essence from making people laugh.
But what would the equivalent of a closest be in medieval Europe? I imagine in practical terms a chest, but psychologically . . . hopefully not the outhouse.
Faeries would be lurking outside the home, or the castle. Kids, except the richest, would not necessarily have beds. Houses would be quite small, so kids could be quite frightened of faeries coming down a chimney or through the door, unless the proper prayers were said or folk-charms performed.
You'll note that most faerie tales take place in a forest. People are afraid of the world beyond the village. Approach accordingly.
Kids except children of wealth will not have their own room and might well share their parents bed. How people had large families in this situation is something that some modern individuals find hard to understand.
You could use the Simulacra option of the Verditius Automata, though they wouldn't be intelligent enough to be proper Transformers. You'd need to find a way to bind a spirit into the Automata, perhaps using a variant of Spell Binding and Spirit familiar mysteries, or a breakthrough combining Automata and Awakening mysteries.
Having instilled the Spirit into the Automata, elements of the Automata could be enchanted as Magic Items, as per normal, and could be activated by the inhabited spirits.