Y/n L/n

Y/n and his friend are found inside an iceberg by two siblings after being in it for a long time.
What will they do when they hear about a war that has been going on for 100 years.
And what is Y/n going to do to stop the fire nation from taking over the world.
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Book 1: Water: Writing.
Book 2: Earth: -
Book 3: Fire: -
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(None of the pictures or videos I use belong to me)