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.
Well, Tumblr can be a great place too. There are many Young Justice fanfic communities on Tumblr. You can search for tags like 'Young Justice Martian OC' and you'll likely find some great fanfictions shared by fans. Some fans also post links to their works on Twitter, so it's worth checking out the #YoungJustice hashtag as well.
You can start by creating shared experiences. For example, they could be paired up for a mission where they have to rely on each other to succeed. This builds trust. Another way is through misunderstandings. Maybe the OC does something that Miss Martian misinterprets, and they have to work through it to understand each other better. This adds depth to their relationship.
A possible plot is that the OC is a new recruit to the Young Justice team. Miss Martian is assigned to train the OC. At first, they don't get along because the OC is headstrong and doesn't like taking orders. But as they face various challenges together, like fighting against a powerful enemy that targets the team's weaknesses, they start to understand each other better. The OC could also have a secret past that Miss Martian helps uncover, which deepens their bond.
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.
In my opinion, the fanfictions that focus on their friendship turning into a romantic relationship are some of the best. It's interesting to see how they navigate their feelings for each other while still being part of the Young Justice team. They both have such different personalities - Superboy being more brash and Miss Martian being more empathetic. When these two personalities interact in a romantic context, it can create a lot of drama and sweet moments. Also, fanfictions that show them training together and growing in their powers side by side are really cool.
Another common theme is her powers. Writers love to create scenarios where she has to use her telepathy or shape - shifting in unique ways. Some fanfictions have her using her powers to solve mysteries within the Young Justice universe. It adds an interesting layer to the stories.
A good one would have well - developed characters. The OC should have a unique personality and backstory that makes them stand out. For the Martian Manhunter, the writer should stay true to his character traits like his telepathy, shape - shifting, and his sense of alienation from being the last of his kind. If the story can explore these aspects in an interesting way, it's a start.
The appeal lies in the freedom to create. With an OC, you can shape a character exactly as you want. You can give them a backstory, motives, and relationships that are unique. When paired with Superboy, it can lead to some really interesting storylines.
How about a villain named Shadowstrike? He's an assassin with shadow - based powers. He was trained in a secret organization but turned against them. In the Young Justice fanfiction, he could target the heroes because they represent the establishment that he hates. He can move through shadows and use them to surprise his opponents.