Perhaps he has a very studious personality. He might be more interested in the academic side of magic than Harry was. He could be spending all his free time in the library, researching ancient spells and potions. This would make him a bit of an oddball compared to Harry who was more into practical magic and Quidditch.
He could be really outgoing. Maybe he's the type who makes friends easily and is always the life of the party at Hogwarts. Unlike Harry who was a bit more reserved at times, the younger brother could be constantly getting into adventures and dragging Harry along with him.
He could be really mischievous. He might play pranks on Derek all the time, like hiding his shoes or putting salt in his coffee by mistake. But all in good fun, of course.
She could be very brave, just like her father. Given her family's history, she might be fearless when facing challenges. For instance, if there's a dark wizard on the loose in the wizarding world, she would be the first to step up and try to stop them.
This fanfiction concept is really interesting. Harry being Draco's younger brother would mean a different upbringing for Harry. He'd have access to the Malfoy's wealth and status. However, his personality might still shine through. He might be a Slytherin with a heart of gold, trying to change the family's views from the inside. His relationship with Dumbledore would also be different as Dumbledore might see him as more of a 'project' to save from the Malfoy influence.
Well, you could find fanfictions where Harry's relationship with his famous brother is the central theme. It might explore their sibling rivalry, or how they support each other in the face of magical challenges. Some might also delve into Harry's efforts to carve his own identity.
There are countless adventures they could embark on. They could travel to outer space together, with Superman guiding Harry through the vastness of the cosmos. Harry could use his magic to protect them from any strange magical phenomena they might encounter out there. Or they could go on a quest to find a lost artifact that has the power to both enhance magic and Kryptonian powers. Along the way, they would face many challenges. They might have to deal with other superheroes or wizards who are jealous of their combined powers. They would also have to learn to trust each other completely, as their different powers and ways of thinking could sometimes lead to misunderstandings. But through these adventures, their bond as brothers would grow stronger.
They might go on adventures like exploring the Forbidden Forest. Since Harry is Doms' younger brother in this fanfiction, they could be sneaking around the forest looking for magical creatures that are rumored to live there.
They could have a really complex relationship. Draco would be protective yet also have his Slytherin pride. Harry might look up to Draco in some ways, like for his knowledge of the wizarding world. But they could also have their disagreements, especially when it comes to things like blood purity. However, at the end of the day, the brotherly bond would still be there.
A fleet of magical ships is also a possibility. These ships could be made of magical wood and have various enchantments. They might be able to travel between different magical dimensions or through dangerous magical waters. Maybe they are crewed by a mix of wizards, magical creatures, and even house - elves, all under Harry Potter's leadership in the fanfiction world.
She could be really shy. Growing up in Naruto's shadow, she might be hesitant to show her true self. Or she could be the opposite, very outgoing and confident, trying to make a name for herself separate from Naruto.
The baby could be really feisty. Since Sesshomaru is a powerful demon, the baby might inherit some of that strength and show it early on as a spunky and fearless personality.