Mu los fin kiir do Bormahu

Dragons are said to be the immortal children of Akatosh. They were indigenous to Akavir, but when the Tsaesci attempted to "consume" them, they fled to Tamriel. As the dragons were created by Akatosh, they do not mate or breed and all dragons seem to be male. Alduin, who has proclaimed himself the 'First-Born of Akatosh' is said to be the first dragon that came into existence.

As Paarthurnax explains to the Dragonborn, all dragons have the desire for power and domination in their blood. For a long time, dragons have considered those not of their kin to be weak-minded. However, when it comes to Alduin, he still sees even the Dragonborn as a weakling until his defeat in Sovngarde.

The dragons' language, also known as Dovahzul, can be manifested into powerful magic known as a "Shout", or a Thu'um. The Thu'ums are always made up of three "rotmulaag", or words of power. Rotmulaag in itself is a compound word, made up of rot, "word" and mulaag, "strength/power".

In battle, dragons are actually in the midst of a deadly verbal debate. If one of them dies, their life force and knowledge will be absorbed by the victor. This ability to absorb a fallen dragon's soul is granted to the Dragonborn as well as the ability to learn and use Thu'ums effortlessly.

ALDUIN

Dovahkiin, hin kah fen kos bonaar.
Dragonborn, your pride will be humbled.

Alduin is the primary antagonist in this story. After Alduin was "defeated" at the Throat of the World in the Dragon Wars, he was pushed forward in time by use of the Elder Scroll. Alduin is known as the World-Eater in records of Tamriel's ancient history. Alduin would have been responsible for the end of Tamriel and all her inhabitants. The First Dragonborn, Miraak, was supposed to be the warrior that would defeat Alduin but they sacrificed their soul to Hermaeus Mora in order to avoid having to fight Alduin.

In 4E 201, Alduin would be released from his "prison" in the Time Wound and resurface to once again fulfill the prophecy of Alduin's Wall.

PAARTHURNAX

Onikaan ni ov dovah.
Wisdom is not trusting a dragon.

Paarthurnax was originally Alduin's first lieutenant in the Dragon War, but became disallusioned with Alduin's arrogance when his kin proclaimed himself as a god. Kynareth intervened in the war, and instructed Paarthurnax to assist humankind in their fight against the dragons. Paarthurnax taught the humans the Voice, and when Alduin was banished by the Elder Scroll, Paarthurnax chose a life of thousands of years of solitude and meditation on the Way of the Voice in comparison to his old life of tyranny alongside Alduin.

The Blades, former dragonslayers and bodyguards of the Septim emperors, were mostly destroyed by the Aldmeri Dominion in the Great War. The only two that remain are Delphine and Esbern, who both wish to see Paarthurnax brought to justice by the Dragonborn.

ODAHVIING

Faas nu, zini dein ruthi ahst vaal.
Fear not, my honor holds my rage at bay.

Odahviing was another dragon that served Alduin during the Dragon War. He was Alduin's right-hand dragon and was "killed". His body was buried in Riften though because his soul was not devoured by another dragon, Alduin was able to resurrect him in the fourth era.

When Odahviing is trapped by the Dragonborn in Dragonsreach, he betrays Alduin by pledging his loyalty to the Dragonborn instead and assists the Dragonborn by taking them to Skuldafn, where the Dragonborn enters Sovngarde and finally defeats Alduin alongside Felldir the Old, Gormlaith Golden-Hilt, and Hakon One-Eye.

After Alduin's defeat, Odahviing extended his service to the Dragonborn by offering his aide in battle, proving to be a very useful ally.