Fluogens are born when two existing Fluogens come together and forge a new being in fire of creation. They take a special glass originally found in meteors, and blow the glass into the shape of their child. Once they breathe their own life essence into the glass, the essence of both parents mix and brings life to the glass. This essence will always flow and circulate through their body, and even has a bioluminescent quality.
With that new life the child begins to grow and develop their soft outer-skin. This skin protects the glass from possible chips or breaks, with the notable exception of a diamond on their chest, and their horns. Though it's only noticeable with their mouth open, their teeth and tongue are made of their glass. Though the teeth never show the essence, the inside of their mouth is always colored with their essence. Their eyes are glass as well, showing their essence in the rounds of their eyes. This is enough for them to see, even without pupils.
Of course as they grow they also develop their own sense of style and express themselves!
On the rare occasion that the outer skin never develops, or a break occurs before the skin grows, the essence of the Fluogen begins to leak out of their body. It takes an effort to keep their essence together, so these Fluogens tend to be more tired than most.
These breaks can even occur around the neck! Creating a rather unique but interesting case of a headless Fluogen.