Rugaru

Rugarus are genetically modified carnivore humanoids which feed on 'long pig': human flesh. They start out human for all intents and purposes, but they will suddenly begin craving large quantities of food. This condition is not a virus; rather, it is passed down genetically. A person who possesses this gene will eventually give in to the urge to feed and will devour a human. The change starts out with an increased hunger for all food, but quickly changes into a craving for flesh, specifically human. The change itself is very fast. Once the Rugaru gives into its desire to feed on human flesh, there is no going back; the Rugaru will lose its human appearance and change into a monster.

Although it is believed by some that a person with this gene can overcome their curse, no Rugarus are known to have been successful in this. Apparently, the final change can be avoided as long as the Rugaru resists eating human flesh. Unfortunately, the urge is extremely strong and is practically impossible to ignore.

Metamorphosis
The first time Sam and Dean hear about Rugarus is from a fellow hunter named Travis. He sends them to watch Jack Montgomery, a man who is about to become a Rugaru. Jack is showing signs of his impending change but has managed to resist it so far. When Sam and Dean later meet Jack and warn him about what's happening, Jack kicks them off of his property rather than heeding their words. Later on, he climbes to the window of a woman, nearly charging at her, yet retreating. Afterwards, coupled with Travis's intervention, Jack is pushed towards his first bite and the final step, making Jack a fullgrown Rugaru.

Abilites
Super Strength- Rugarus are stronger than the average human and can easily break bones.

Speed- Rugarus are essentially like animals. Speed is a necessity, allowing the Rugaru to catch its prey.

Flesh Eating- Its primary motivation and food source.

Weakness
Fire- Rugarus can only be killed by fire. Hunters need to burn them alive.

Behavior
After consuming human flesh, the Rugaru will act as a predator, often eating violently and moving on all fours. Their human emotional side becomes less active, yet they retain all physical abilities.

Outlook
Rugarus look nearly completely human, aside several exceptions:

Large wrinkles, appearing on their faces.

Fullgrown Rugarus obatin demonic, pitchblack eyes, while unchanged Rugarus have red, bloody scleras.

Appearances

 * Metamorphosis
 * Swan Song (Mentioned Only)
 * Caged Heat (The monster Sam and Dean hand to Crowley's minions)