The Flame Tree Disorder
There are a few symptoms that define an Aphex with FTD. An eternal flame around their eyes and a bright glowing in their chest. Due to the rarity of this illness and its inability to spread to other creatures society do not fear it's spread. Flame Tree Disorder originates from a unique fruit only found in the depths of Gonewell, and is very rare and prized. Only found on the black market, the fruit is primarily used for two distinct purposes; poisoning others and a death-bed cure. The juices of the Nian Fruit (The fruit that causes FTD) is very potent, only needing a drop or so to affect a being. Once in the bloodstream, 95% of cases end in instant combustion, turning the being who consumed the liquid into a pile of burning ashes. The remaining 5% go through an experience called "Husking". This is extremely painful and lasts around 24 hours. 
 
What are Husks?
Once Husking has begun, the victim's internal organs are set alight, becoming so hot that they eventually mold together into a single fiery core inside their chest. If the species does not contain common organs, any internal matter turns into this core. A magical flame runs through their veins, powering the body with energy from their chests. Their ribcage may also undergo changes (if there is no ribcage, one is generated). They become flexible and wrap around the core to protect it. If this core is damaged or removed, it would permanently kill the Husk. A Husk's flame is also a key signature of its condition, being its primary energy it fills their bodies but can also change colour depending on the Husk's mood. This "fire" is more of magic descent, meaning it can survive in water and wind. 
 
Normal Form:
Husks have a few key defining traits such as a glowing chest and flames around the eyes, however in their normal form these flames are only warm, and their skin is constantly full of heat. A Husk's normal flame colour can be any colour, but will change upon emotional changes, so it isn't always a clear depiction of their current mood.
 
Typically, Mood colours follow the chart below but can vary on more unique moods or preferences:
Happy: Yellow
Envy: Green
Angry: Red
Cautious: Orange
Sad: Blue
Depressed: Black
Paranoid: White
Love: Pink
Stressed: Purple
 
 
Inferno Form:
Inferno forms occur when the Husk experiences intense emotion, such as anger or sadness. Their bodies erupt into uncontrollable heat and their chests expand open to release this build-up of energy, exposing their cores. Flames around their eyes usually become more intense, and their tail can turn into flame, which can be further used as a weapon, as the fire in this form is extremely hot. In most cases, the coat becomes darker, more "scorched" like. This form is only temporary and usually fades once the character has calmed down or run out of energy, in which the Husk can die.