Please try to put aside all of your ideas about dragons. I am not here to explore the idea of the fire-breathing, scaled creature of today's movies. In my mind, the dragon is different than that and much more than that.
Dragons in The West
The Persians called the primordial chaos a "dragon," but that could have been a translation issue. We really have no English word for the thing that Tiamat was, but it was her body that was used to create the universe. This kind of dismemberment cosmogony was exposed to the cultures of the Ancient Neat East, including the Semitic peoples, before the writings that became the Bible were written. In Isaiah 27, we find mention of "Leviathan" as the dragon of the sea. Remember that the sea was present at the time of creation - "and God parted the waters and made dry land appear" - the sea was the primordial ocean, the representation of the chaotic world before it had any ordered form, and it was out of this that the world was formed. An example can be found in the script of the Hebrews, whose writings did not include vowels. The word "Leviathan" can easily be extrapolated from the consonants in "Lotan," the name of the Ugaritic serpent of the primordial oceans. By the time we reach the formation of the Church in the late second century, the ideas of chaos-beings as serpents were already a part of the religious writings. The element responsible for bringing chaos to the Garden of Eden was, after all, a serpent.
Fast forward 1000 years and the legends written were of knights trying to defeat dragons. Dragons had become the allegorical symbol for the savage and chaotic forces of nature that threatened mankind as he struggled to survive and expand his civilized society. Always at the edge of the pagan village was the expanse of the unknown, into which people were regularly lost. The dragon became a tangible image for the formless unknown of Nature's chaos, and the knight was a symbolic hero of the kingdom, who could drive back the chaos, providing safety for the king's subjects.
By why were dragons always serpents? Snakes cannot be tamed. They cannot be taught tricks like dogs or cats. They do not have fur or hair like our pets or ourselves. They have no limbs and eat by swallowing their food whole. They are a creature that appears completely alien to us. They carry poison in their mouths and can kill us or make us very sick with a scratch, perhaps leading primitive man to think that their whole body may be poisonous, and so unsuitable for food. For all of these reasons, they are the target one of mankind's oldest and most prevalent phobias. The striving for the destruction of dragons in western culture could be based on mankind's combined fear of snakes and untamed nature. The dragon of these early medieval stories isn't really a dragon, it is the unknown, chaos, or simply the phobia of snakes. If we took all of the stories of dragons in western culture and changed the word "dragon" to something less allegorical - perhaps just "snake" - those stories would still do what they are designed to do. This means that the dragon of eastern culture formed separately, fulfilling very different roles in the mind of mankind.
The Persian idea that dragons were a primordial force is not far from the concepts of dragons in the Far East. In the East, however, dragons were not simply the chaos at the beginning of the world. They were many of the powerful forces of nature upon which early mankind watched with wonder and attributed to the divine. Dragons inhabited streams, lakes, oceans, mountains, fire, and storms. They gave counsel, protection and luck. It's clear that in the East, dragons were nature spirits, much like the spirits of American Indian paganism, the fairies of the Celts, or the hosts of nymphs, Nereids and satyrs to the Greeks. In the East, however, these spirits were very powerful in the schema of the universe, being godlike and often worshiped.
Dragons in the Present
Based on western cultural history, and our capitalistic propensity to make all things cute and salable, dragons have fallen back into favor. Through cartoons, comic books, movies and novels, we can experience them as friends or as enemies, but marketing will always provide us with a collectible figure that we can keep close to us, no matter how cute or ugly. In more recent years, the cute concepts of dragons have gained ground. Unfortunately, though these concepts ushers dragons back into our lives as objects of affection, we are still missing what dragons truly are.
Dragons are high beings in our universe. They are powerful nature spirits with whom we can build working magickal relationships. The next time you spend some effort working to communicate with the essence of Eagle, or Wolf, or Coyote, don't forget the unsung power in Nature: the Dragon. If the name summons to mind too many fantasy movies to take your efforts seriously, try using one of its original names like "Ryū" in Japanese, or "Lóng" in Chinese, which is the sound of thunder! Dragons will not work with those who are dishonorable or weak of heart. They are powerful beings who prefer to work with those who understand power. No frilly, fluffy-bunny pagan book is needed to learn dragon language or to find a dragon grotto. All that is required is to hold in your mind the correct concept of them, believe in their existence, and provide them with ceremonies that show them honor. They will soon find you and will begin slowly building a relationship with you through your intuitive mind.