Avatar: The Last Airbender (X Male OC): Water

Jinhai is a member of the water tribe in the South Pole, wanting to take revenge for what happened to his father and mother after the Fire Nation attacked.

As the childhood friend of Katara and her brother Sokka, they always supported each other in everything they gotta do to make the most of their time, but Jinhai always hung out with Katara more, knowing how they always got along very well and Sokka being the sexist guy that he is.

However, while Jinhai and the siblings fish one day, they come across an iceberg that contains a bald headed kid named Aang, discovering in the process that he's the last Avatar and airbender.

After getting to know Aang and saving him from the Fire Nation, who took him away to keep the village safe, the kids embark on a journey that will meet its challenges and tribulations.