Daneasaur 
"[@Background Pony Number 17":](/1457185#comment_6214016
)
Chances are it may be similar to A Flight Of Dragons in that the gemstones he eats provide fuel when he digests them (a gas that is transferred to a special dragon organ that contains it) and the sparks come from his "thimble", which was a small organ on the roof of the dragon's mouth that produced enough electricity when stimulated to spark a flame.
... This also means that if he ever deep kissed someone and they kissed him back, they would run the possibility of licking said thimble.
"
[Here you go.":](https://www.youtube.com/watch?v=j0j0Bjy6hFc)
Just keep in mind that the science is dated.
Chances are it may be similar to A Flight Of Dragons in that the gemstones he eats provide fuel when he digests them (a gas that is transferred to a special dragon organ that contains it) and the sparks come from his "thimble", which was a small organ on the roof of the dragon's mouth that produced enough electricity when stimulated to spark a flame.
... This also means that if he ever deep kissed someone and they kissed him back, they would run the possibility of licking said thimble.
"
[Here you go.
Just keep in mind that the science is dated.