Amphivena, the Fear Eater

We hadn't sleep in days. We dared not to close our eyes, for not to come across the terrible monster that is known as Amphivena. None of us wanted our minds eaten, or our brains lost so we kept at it. Keeping each other awake, through shouting, slapping and throwing water in our faces. To this day I still don't know if Amphivena would appear to us or not. But it was a risk, none of us was willing to take. - Recounting History: Mythos, Legends & Lore

Summary

Amphivena is a tale, a legend told to anyone who will listen about a two headed beast, one head on its shoulders and one at the end of its tail, that will come to those who are being eaten by guilt and terrorized by their own morality to consume their fears and leave them in an eternal panicked state, or even break their minds.

Historical Basis

There is no historical basis for this legend and no sightings of any two headed monstrosities that eat fears have been reported. However, there have been some monsters that have been connected with supernatural phenomena that might be close to the description. But none that match it even a bit closely.

Spread

The legend has been recorded, orally and in scripts since before The Blight. It has no known origin, but it has been passed down from generation to generation. It's initial use seems to be to guilt children into sleeping, or make them afraid enough to stop questioning their parents.
It's spread seems to have been declining recently, as more and more kids appear confused when asked about it. This is attributed to Illion forbiding the teaching of the myth to children, with The Heptarch following suit. Some other neighbouring kingdoms appear to also be following their paradigm.

Variations & Mutation

The main variation of the myth says that the monster will come at night, to those who have commited acts they feel guilty of. The creature senses the guilt and hovers over you as you sleep. While it opens its mouth and sucks your fears, its second head, the one on the tail keeps watch for anyone who might wish to attack. After the monster consumes the fears, the main head shares some of it with the small head.
The main aspects of the myth, the two heads and the fear eating, remain across cultures. The myth's spread has been discouraged in Illion and an increase in children feeling safe has been reported, although the means that these statistics have been acquired are shady at best. In the east, where the myth is more prominent, variations exist. For example in Zadelair, the monster is believed to have wings and resembles a lizard while it doesn't only eat your fears but also feasts on your hopes and dreams. While in the southern parts, in Rhodesia and The Free Forests, the tales mention the beast can float without wings and eats your fears and sucks your mind out of your nose.
It is also known Amphisbona, Amphiosta, or Amphilype.

Cultural Reception

The myth is heavily questioned by scholars and historians. A creature that feeds on fear and guilt, that is able to travel within moments across the world and can sense fear across continents seems rather implausible. And reports of people who have committed crimes, felt guilty but were not attacked have been documented.
The believers speak in reverence of the creature, asking that people must believe it chooses its targets based on some autonomous process that they can't explain. Discussions have been made on occassion, but the existence of the creature is heavily debated still.

In Literature

The creature has been references in numerous works, fictional or not. Most commonly it is been described as an ethereal presence that haunts people who are feeling guilt and fear, used metaphorically.

In Art

The picture that is believed to best describe the creature, shows a feathered lizard, with a fleshy tail that ends in what is a smaller version of its head. Each head is crowned by a pair of horns while the eyes of the creature shine a violent shade of purple, as it has been described. In some pictures, the creature is depicted as eating it's own second head, believed to occur when it has no fear to feast upon.