Dragons are fireless until they undergo the Hroom, the traditional draconic ceremony where a fledgling dragon will go out into the world and make a bargain with a spirit of elemental fire to live in their soul in a state of mutual symbiosis. The spirit receives shelter and nourishment, while the dragon receives a source of elemental fire, which it can only now use to defend itself.
In many draconic cultures, the Hroom marks a dragon’s coming of age, a time to recognize that a dragon is now of a proper age to hold a weapon and defend itself. Some dragons believe that it is only by bonding with an elemental spirit that a dragon has a soul, and that a dragon is only a whole dragon when it has both the mortal shell and the inner spark.
There has been a backlash to this in recent centuries, of course. Fledglings these days are going out and making bargains with all kinds of things. This is usually spirits of elemental lightning and ice, but more than one dragon has come back to their clutch with a fairly bewildered witch.