Just… Ew: LotR's Dragons Creation Theory Is Actually Quite Disturbing
Tolkien added so much depth into his novels that much of Middle-Earth's history and origins remain unexplained.
Unlike the races of elves, dwarves or orcs, in the books the existence of dragons appears as much more familiar; relating to well-known myths and legends. Yet even their creation is disputed among fans. The most prominent theory that Tolkien likely considered the birth of dragons in LotR is much more disturbing than you would have first thought.
Many theories surrounding the creation of dragons in the Middle-Earth centre around the corruption or spawning of one race into another. Which was how most of the races within the lore are said to have come into existence.
Some theories suggest that dragons are corrupted eagles. Others think they are former men or dwarves who have turned to darkness; similar to how orcs started as corrupted elves.
The most likely theory is that Morgoth bred the Maiar with some form of beast. Maybe even one of the "nameless things", from the void early in the formation of the world, who are creatures of pure darkness.
The reason this presents such a discomforting connotation is that to Morgoth, the Maiar are his own kin. In fact, they are the lesser forms of the Ainur (including Morgoth) and similar in a way to his younger siblings.
One ability of the Maiar is they could shape-shift into other manifestations. Meaning, from the orders of Morgoth himself, they could have transformed into a reptile-like form and reproduced with another creature to create the first dragon. To corrupt any of the Maiar and "breed" them to form a new creature seems especially unsettling, and truly demonstrates his turn to the darkness.
What is even more disturbing is that all the beasts and creatures of Middle-Earth are in fact the creation of Morgoth himself. Something he did while helping to form Arda along with the other Valar. To breed them with the Maiar is alarmingly similar to mating your sibling with your child. No wonder all the dragons were evil.
After the dragons' creation, they continued to follow Morgoth until his exile to the timeless void. He used them as war beasts in his fight against the Valar. Ultimately they fled north, where they were drawn to the kingdoms of the dwarves for their mass collections of gold and treasures.
Ultimately, LotR fans will never know the full story of how the dragons were first introduced to Middle-Earth and where they first came from. If this theory is correct, according to Tolkien's original intentions they are the product of a forced pairing. Which explains how such powerful and corrupt creatures as Smaug ever came to exist in the first place.