Where did the Chromatic/Metallic Dragons come from?

Question

In the AD&D Monster Manual, the Chromatic (evil) and Metallic (good) dragons are introduced. Each color of dragon has a different habitat, personality and breath weapon. (Or two breath weapons, in the case of the Metallic dragons.) Where did these various traits come from? Were they exclusively created for D&D, or were they inspired by a certain fantasy work?

As an example, the Brass dragon has two breath weapons: cone of sleep gas and a line of fire. They are said to be very talkative, they live in deserts, etc. Is that based on a specific folklore, mythology, a work by a certain author, or was it pulled from thin air?

Answer 1

Gary Gygax answered this question in an EN World interview, and at more length in Slayer's Guide to Dragons.

Originally there were the five chromatic and evil dragons, each with a color that suited their breath weapon, and a sixth good dragon patterned on the Oriental model of that imaginary creature. As it was both or different origination and alignment I decided to empower the gold dragon so as to more closely resemble the potent Oriental sort. So it got more of everything, including two breath weapons.

There came a time thereafter when more metallic dragons were desirable so as to expand the roster of good, Oriental-type ones. Thus all of them were modeled on the gold dragon template, had two breath weapons.

Logically, with metal value being used as the basis for potency, platunum (Bahamut) being the highest, then gold and silver, the sequence should have been platinum-gold-electrum-silver-copper-bronze. However, I thought bronze looked more potent than copper, and skipped then to brass—that metal conveying some not-so-benign connotations.

See https://ia804709.us.archive.org/29/items/enword_gary_gygax_qa_threads/enweggqa05.pdf for the longer quote.

Answer 2

Tiamat and The Chromatic Dragons

In Mesopotamian religion Tiamat is a Chaos Beast, a primordial goddess of the ocean and is depicted as a serpentine dragon. The image we see of Tiamat in D&D is based off of another creature known as Lotan who is a seven headed sea serpent or dragon from Ugaritic myths. The reason Tiamat (and therefore the rest of the chromatic dragons) is evil is she is also based off of European dragons who were also portrayed as malevolent. Now the origin of the usage of the chromatic for the chromatic dragons I think would be Smuag since he was red and also evil.

Bahamut and The Metallic Dragons

Bahamut, from the Arabic myths we know as the Arabian Nights, was a fish and also one of the layers that supports the earth. Bahamut seems to be more based off of Eastern dragons; if you look at this picture of Bahamut drawn directly from the 1st edition monster manual, notice the "beard" he has and also the Chinese dragon historically was a symbol of the emperor of China who would have been considered the most honorable figure possible.

In the Chinese Zodiac the Dragon is a creature of myth and legend. A symbol of good fortune and sign of intense power, the Oriental Dragon is regarded as a divine beast - the reverse of the malicious monster that Westerners felt necessary to find and slay. In Eastern philosophy, the Dragon is said to be a deliverer of good fortune and a master of authority. Therefore, those people born in Dragon years are to be honored and respected.

So I think all of these thing helped influence the alignment of the dragons and the division between good and evil dragons.

Breath Weapon

Now as far as the breath weapon, most historical dragons seem to exclusively breath fire, although some dragons could control the weather, which I think inspired some of the other breath weapons such as Ice breath and lightning breath.

Dragon Intellegence

Historically Dragons were often portrayed as Divine or Astral beings and we're seldomly unintelligent.