Well, since I'm pretty much the only person on CL that actually base themselves around dragons from the Nine Realms, heres what they are basically.

Dragons from the Fire Realm

Eggs-Believe it or not, the eggs from the different realm are each unique, the Fire realm egg is probably the smallest of each of them, and the dragon in it generates extremely hot air around it, the eggshell is a pecial material that conducts heat and amplifies it tenfold, so anyone trying to steal/harm the egg in any way will literally get their hand burnt off.

Growing up-From the age of 5 years old the young fire dragon is taught about hunting and combat, they are able to breath their first mediocre fireball at the age of 13, at 20 they are able to breath average level fire, and are then put to the test in a fight against a dragon from another relm, usually an Ice Dragon, ince the Fire and Ice realm aren't exactly in good terms with one another, being opposite elements and all.

Adult-When a Fire Dragon reaches the Age of 260 they are considered an adult, they are now able to breath fully fledge fire that could easily mealt through boulders, and are now fully trained in combat, the temperature of their fire increases as they age, and they gain more control over it.

Other Facts: Out of every ingle Fire Dragon, there is one, it is the Alpha Dragon, out of all time, there have only ever been two people to ever defeat this dragon, all the others have died.

Nature: Fire Dragons are probably the most aggressive of the Nine Dragon Species.