Dragonborn

Long ago, before The Cleansing, the population of the dragons was made up not only of true dragons, but also the first Dragonborn, originally called the Scaletouched. After the war, many of the Scaletouched died or went extinct, but the small remnants that survived the conflict met a different story than the true dragons that went into hiding. Scaletouched were not mortals by any accounts when they first roamed this land. They were pieces of Zauth, The Greatwyrm, granted form and self to become his people and spread the dragon's will all across their territory of the Draconic Lands in East Milnir (Before the Realm became separated during The Cleansing). When Life and Death were created, the Scaletouched that remained were given another chance, to become their own people independent of the will of the True Dragons. In exchange, they'd become severed from them, only maintaining an innate connection to the elements they originally held within in their creation, and a part of them would instead be spread across the new life that was to populate the Lands in their rebirth to grant them power and strength. As such, Dragonborn were created.
Dragonborn are not exactly their own kind, in the sense that they did not belong to the first races that the Gods molded (Humans, Elves and Dwarves). Instead, originally, every human, elf or dwarf had a chance to instead be granted the features of the Dragonborn upon their creation. In the beginning, this meant some human children, Elven gemstones and new Dwarves were gifted with Draconic traits such as scaled skin, the ability to breathe an element they were tied to and had their physiology changed to accomodate for these abilities. The original Dragonborn lived hard lives during these times, as not all communities were as accepting of these newfound draconic traits in their offspring, and many were shunned because of this. Some communities went the other direction, seeing Dragonborn as a gift from the gods themselves and many were placed in positions of power and reverence due to their draconic blood. When two Dragonborn came together, they would be capable of reproducing like humans to create another Dragonborn. If a Dragonborn reproduces with another race, there's a 50/50 chance the child will be another dragonborn, or the race of the other parent. Slowly but surely, this meant the Dragonborn settled as their own race in the realm, and became part of the populations of a majority of the communities that make up Milnir today. Cases of Dragonborn born from non-dragonborn parents have become rarer for a reason still being studied, but the chance remains nonetheless.
However, there is one more method of creating a "Dragonborn", although it is much darker... In Ign, territory of the Draconic Enclave, The Dragon Lord Zephyrion has found a way to turn men into Scaletouched under his command. Unlike Dragonborn, these new Scaletouched are more animalistic in their draconic features and are bound to their True Dragon overlords, not being granted a will of their own and forced to serve without question.
If you choose to play a Dragonborn, you gain the following feature in addition to any features granted by your race:

Dragon's Blood

You tap into the innate energy of your draconic lineage and unleash the wrath of the dragons upon your enemies in a wondrous transformation. As a bonus action, you gain the following benefits:

• Immunity to the damage type associated with your ancestry

• You sprout wings which grant you a 30 foot fly speed (Alternatively, instead of sprouting wings your claws may become sharper or your body may shift in some way, granting you a burrow speed equal to half your walk speed and a climb speed equal to your walk speed)

• Your breath weapon's damage dice become d8s instead of d6s, and you can use your breath weapon a number of times equal to your proficiency bonus

These effects last for 1 minute or until you dismiss the transformation as a bonus action. You can assume this form once per day. At 5th level, you can assume this form twice per day, and your fly speed becomes 40 feet (Burrow speed is equal to your walk speed, and your base speed goes up by 10 if you chose not to sprout wings.)