The plot could involve Byakuran getting lost in Harry's world. Luna discovers him and they become friends. Then they introduce Byakuran to Harry. Together, they form a sort of detective group within Hogwarts. They start to investigate strange happenings around the school that are related to a dark force from Byakuran's world trying to invade Hogwarts.
Byakuran might have some unique powers from his own world. His powers could be used to create diversions or solve certain physical challenges. Luna, with her perceptive and dreamy nature, can often see things others miss. She can sense hidden motives or spot secret passages. Harry, of course, has his magical skills from Hogwarts like his proficiency in spells. His ability to fight dark magic is crucial. So, Byakuran's physical power skills, Luna's perceptive skills, and Harry's combat magic skills work together well. For example, when facing a dangerous enemy, Byakuran can hold it off physically, Luna can figure out its weak points, and Harry can then use a spell to defeat it.
Fanfiction often explores various relationships, but this particular topic might not be in line with the spirit of the original 'Harry Potter' series. There are many other great fanfictions that focus on their friendship or adventures without delving into such inappropriate content.
There are fanfictions that focus on their study of magic together. For example, they could be researching ancient spells or exploring new magical creatures. This would be more in line with the magical and innocent nature of the 'Harry Potter' world.
It could be that he is wrongly perceived as dangerous. After all, he has survived the Killing Curse as a baby and Voldemort is always after him. People might be afraid to get close to him for fear of getting caught up in the dark wizard's wrath.
One of his friends could be a young werewolf who is struggling to control his condition. Harry, having faced his own challenges, would befriend him and help him find a way to live a more normal life in the wizarding world.
For Harry, his growth could be shown through how he becomes more open - minded. He starts to embrace Luna's quirks and her different way of seeing things, which in turn makes him more accepting in general. For example, he might initially be a bit hesitant about Luna's belief in some of the more out - there magical creatures, but as they date, he starts to see the beauty in her imagination.
Friendship turning into something more is also a prevalent theme. They start as friends or comrades, and then gradually, feelings develop that are deeper than just friendship. This theme allows for a slow - burn type of story that can be very engaging for readers.
One great fanfic could be 'Luna's Influence'. In this fic, Harry starts to notice Luna's unique perspective during a Hogwarts class. Her calm and other - worldly view during a chaotic time in the wizarding world draws Harry in. They begin to exchange ideas about the mysteries of magic and the threats they face. Another might be 'Friendship in the Shadows', where they bond over their shared experiences of being somewhat outsiders in the Hogwarts community.
There could be. For example, the baby might inherit some very special magical abilities from both Luna and Harry. It might be able to communicate with magical creatures in an even more unique way than Luna, or have some of Harry's famous courage in a new form.