Maybe his Martian friends.
His family members might come to his rescue. They could use their advanced Martian technology to track him down. They might have some special tools or abilities that are specifically designed for such situations. Also, there could be some kind of Martian spirit or guide that appears to him and gives him the guidance he needs to survive and get out of the hole.
It could be an old and wise Martian elder who has knowledge about the underground areas. This elder might have been waiting for someone to discover the hole and the secrets beneath. Or perhaps some small, friendly underground creatures that are curious about the boy and decide to assist him in finding his way out or exploring further.
Perhaps he'll discover an ancient Martian civilization. There could be old structures, artifacts, and knowledge that has been long forgotten on the surface. He could become the key to unlocking the secrets of this lost civilization, or he could accidentally set off some sort of mechanism that has been dormant for ages, which could lead to various consequences, either good or bad.
One of the main characters could be a scientist. When the martian boy falls to earth, the scientist might be the first to discover him. The scientist would be curious about the boy's physiology and technology from Mars. Another character could be a young girl. She could befriend the martian boy and teach him about human emotions and relationships, which are very different from what he has on Mars.
Well, perhaps the young Martian boy is on a mission in his own planet but something goes wrong and his spaceship crashes on Earth. He then has to figure out how to survive in this strange new world with different gravity, air and cultures. He might meet some friendly humans who help him adapt and in the end, he could either find a way to go back to Mars or choose to stay on Earth.
A young shower boy in a story might be energetic. He has to move around a lot to clean the showers and keep things in order.
A theme that sometimes pops up is teamwork. Since they are part of a team in the original series, fanfics may focus on how they work together in different scenarios, highlighting their individual strengths and how they complement each other. Also, the theme of acceptance can be seen. For example, Beast Boy might have to accept Miss Martian's different cultural background or powers, and vice versa, which can create interesting storylines in fanfics.
εοΏ½οΏ½οΏ½ππΆπ¨π¨π¨π¨π¨π¨π¨π¨π¨π¨π¨π¨π¨π¨π¨π¨π¨π¨π¨π¨
There's also a fanfic called 'Miss Martian's New Path'. In this one, she has to face a new enemy that targets her specifically because of her Martian heritage. It's full of action and also some really touching moments as she leans on her friends in the Young Justice team for support.
First, do your research on the Young Justice universe, especially about Martians. Know their powers, culture, and how they interact with other characters in the show. Then, create a well - developed OC. Give them a unique personality, backstory, and goals. For example, your Martian OC could have a conflict between their Martian heritage and their new life on Earth.
In some fanfics, their sibling relationship could be explored through flashbacks. For example, showing how they were separated as children due to some intergalactic event. Then, in the present, they are reunited and have to catch up on all the years they missed. This could involve them learning about each other's cultures and dealing with the differences between being a Martian and a shape - shifter.
A key element would be the discovery of their relationship. It could be a shock to both of them and the reactions would be interesting to explore. Another element is how they interact with their shared friends and teammates. Do they keep it a secret or are they open about it? Also, their different powers could play a role. Maybe they combine their powers in unique ways to solve problems because of their new - found bond.