You were about five years old when your younger brother was born. You were jealous of the attention he received, but you also noticed that your mother turned almost hostile towards your family's pet cat. The cat was never allowed anywhere near your brother. When you asked why, your mother mentioned an old folk tale about how cats would steal the breath of sleeping infants – not that she believed it literally, no, but that what really happened was cats would climb on top of a sleeping infant and accidentally smother it.
Late one night, you got up from bed to go to the bathroom. Your brother's nursery was across the hall from your room, and you saw the door was cracked open. Just big enough for a cat to slip through. Worried, you pushed open the door. There, your cat had perched delicately on the side of your brother's crib. You rushed forward to pull her down, but stopped short when she leaped into the crib and back out in one swift motion, holding a tiny creature in her mouth.
The creature looked like a cross between a cartoon elf and some kind of beetle. Tiny jars, some filled with a strangely luminescent gas that swirled and twisted hauntingly, hung from its belt. The creature struggled against the cat, but was dashed violently to the floor for its troubles. The cat pounced upon it and tore it apart with her claws and fangs, until the creature disintegrated into a yellowish fog. The jars broke in the fight and you could see the luminous gas snake up and back into your brother's crib.
The infant suddenly gasped and began crying, loudly. You went to quiet him, but after a minute your mother came storming in. She yelled at you for letting the cat into your brother's room, and threw the cat out. As she yelled, you could see another of those tiny creatures, riding her shoulder and whispering into her ear. She wouldn't listen to a thing you said about the cat saving your brother, and made sure to lock the cat into the guest room every night.
Three days later, your baby brother was found dead in the morning.