The dragon doesn’t require air.

While the Dragon sleeps, at least one of its heads is awake.

 You can speak telepathically to any creature you can see, provided the creature is within a number of feet of you equal to 10 times your level. You don’t need to share a language with the creature for it to understand your telepathic utterances, but the creature must be able to understand at least one language.

When you’re using this trait to speak telepathically to a creature, you can use your action to give that creature the ability to speak telepathically with you for 1 hour or until you end this effect as an action. To use this ability, the creature must be able to see you and must be within this trait’s range. You can give this ability to only one creature at a time; giving it to a creature takes it away from another creature who has it.

As a dragon, you have the innate ability to shift between a smaller, more humanoid form and your true form. But due to exterior factors, your ability to switch forms has been limited. As a bonus action, you may change into the wyrmling dragon of your chosen type, gaining all the benefits that come with that, while maintaining most of the abilities that you gained in your humanoid form, though not all. You may transform a number of times per long rest equal to half your proficiency bonus rounded down. 

At lvl 12, you can transform into the young form of the dragon you chose rather than the wyrmling.

Bite: 1d8 piercing + modifier. At 10th level, this attack deals an additional 1d8 damage of the element type of your ancestry

Claw: 1d6 slashing + modifier

Your Charisma increases by 2, and one other ability score increases by 1.

You age just like any dragon, but while in a shape shifted form, the age of the body looks more akin to a standard mortal’s perception of age.

Dragon Kin stand at about five to six feet tall, but usually somewhere in the middle. Though certain examples are much larger, leaning 7 to 9ft tall. They have thin, deceptively lightweight bodies around 100 pounds with the larger end leaning towards 160-180 pounds. Your size is Medium-large.

Your base walking speed is 30 feet.

You have draconic ancestry. Choose one type of dragon from the Draconic Ancestry table. Your breath weapon and damage resistance are determined by the dragon type, as shown in the table.

Draconic Ancestry

You can use your action to exhale destructive energy. Your draconic ancestry determines the size, shape, and damage type of the exhalation. When you use your breath weapon, each creature in the area of the exhalation must make a saving throw, the type of which is determined by your draconic ancestry. The DC for this saving throw equals 8 + your Constitution modifier + your proficiency bonus. A creature takes 1d10 damage on a failed save, and half as much damage on a successful one. The damage increases to 2d10 at 5th level, 3d10 at 11th level, and 4d10 at 17th level. After you use your breath weapon, you can’t use it again until you complete a short or long rest.

You can use your Breath Weapon a number of times equal to your proficiency bonus, and you regain all expended uses when you finish a long rest. At 12th level you gain a second variant of breath to use your charges on. 30ftx5ft line, dex save, ignores half and ¾ cover.

You can use your wings to glide, you fall 10ft, for every 1 foot forward in the air you move, your height in the air is reduced by 1ft. At 5th level, your wings have become strong enough to carry you in proper flight, giving you a flying speed equal to your movement. To use this speed, you can’t be wearing heavy armor, or armor you are not proficient in.

Dragons are adapted for living and flying at twilight hours. You can see in dim light within 60 feet of you as if it were bright light, and in darkness as if it were dim light. You can't discern color in darkness, only shades of gray.

You can speak, read, and write Common and Draconic. Draconic is thought to be one of the oldest languages and is often used in the study of magic. The language sounds harsh to most other creatures and includes numerous hard consonants and sibilants.