Let the character have their own interests and flaws. Just because they are in Lennon's orbit doesn't mean they have to be perfect. Maybe they are really into art but are also shy and have trouble expressing themselves. Their relationship with Lennon can then help them overcome some of these flaws.
One idea could be a story where the adopted character discovers a hidden musical talent inspired by Lennon's music. They start writing songs in the same style and end up making a name for themselves in the music world.
To develop the character realistically, start with his relationship with Stannis. Given Stannis's stern nature, the OC might be under a lot of pressure to be perfect. He could be constantly striving to meet his father's high standards, which could lead to insecurities. Also, consider his upbringing in the Baratheon household. He would be exposed to the politics and power plays from a young age, so he should be politically astute and aware of the importance of alliances.
To develop their relationship realistically, start with their initial enmity. Given Dolohov's Death Eater status and Hermione's standing as a member of the Order of the Phoenix. Maybe they first meet in a battle situation where Hermione outsmarts Dolohov, which piques his interest. Then, through a series of forced interactions, like being trapped together in a magically sealed place. Over time, they begin to see each other's humanity. Hermione might notice Dolohov's regrets about his past actions, and he might admire her intelligence and courage.
A realistic development of their relationship would involve them dealing with the jealousy and misunderstandings that might arise. For example, Krum might be jealous of Hermione's close friendship with Harry and Ron. Hermione might misunderstand Krum's busy schedule with his Quidditch career. By working through these issues through honest conversations and mutual understanding, their relationship can grow stronger.
To develop the OC realistically in a Severus Snape rebirth fanfiction, consider their motivation. Why are they interested in Severus? Is it because they see his potential, or do they have their own agenda? Their skills should be developed over time. Don't make them all - powerful from the start. They could learn new spells and magical techniques from Severus or other characters. And their appearance should also reflect their personality. If they are a bit of a rebel, their clothing style or the way they carry themselves could show that. Their growth throughout the story is crucial, as they face challenges and learn from their mistakes, just like Severus does.
The dog's behavior should be based on real dog traits. For example, it could be very loyal to the Avengers. It might also have a love for chasing things, which could lead to some comical or even plot - relevant situations. It should also show fear or caution in dangerous situations, like when facing a powerful villain.
Their relationship could develop through shared experiences. For example, they could be on a mission together to save a city from a monster. During this, they face difficulties and rely on each other's strengths. Saitama's raw power and Genos' technological abilities combine well. This mutual dependence can be the first step in building a deeper connection.
To develop their relationship realistically, start with them getting to know each other's personalities. For example, Ash could share his dreams about becoming a Pokémon Master, and Elesa could talk about her love for fashion and how it relates to her Pokémon. Then, have them go through some small challenges together, like training a difficult Pokémon or helping a lost Pokémon find its way home. These shared experiences will gradually bring them closer.
Their relationship can be developed realistically through shared experiences. For example, going through tough battles together. In combat, they learn to trust each other's skills and judgment. This trust can gradually turn into a deeper connection.
Their relationship can develop realistically through shared experiences outside of their usual Hogwarts cliques. For example, if they volunteer for a dangerous but important mission in the wizarding world. This would force them to rely on each other and see past their initial biases. Another way is if they discover a common interest, like a rare magical creature or a forgotten branch of magic. It would give them a reason to interact more and gradually build a connection.