A new neighbor who is a retired Auror. He could have a lot of stories from his days fighting dark wizards and could act as a mentor to Harry's kids, teaching them about the darker side of the wizarding world and how to be safe in it.
A mischievous house - elf who attaches itself to Harry's family. It could be a bit of a troublemaker, but also helpful in its own way. It might constantly steal little things around the house and then return them in the most unexpected ways, adding some humor to the fanfic.
A magical tutor for Harry's kids could be an interesting addition. This tutor could have some really unique magical abilities and a mysterious past. Maybe a young witch from a far - off land who brings new spells and cultural elements of magic to the story.
A young wizard or witch who has a natural gift for seeing auras. This character could be used to add a new dimension to the sorting process. They might be able to see the true nature of a student better than the sorting hat and could either help the sorting hat or cause some confusion when their observations don't match what the hat decides.
A magical creature in human form. This could be a centaur who has the ability to transform into a human for a short period. They could be a mysterious figure in the 'Magical Me' fanfiction, perhaps having a hidden agenda or being a guide to the main character in a dangerous situation.
A nomadic vampire with a completely different set of values compared to the Cullens. He could be more in tune with his animalistic side and not believe in the Cullens' way of trying to blend in with humans. His presence could cause conflict within the vampire community in Forks and also attract the attention of the werewolves.
One possibility is a young girl who has the ability to control light in a way different from Ruby's speed. She could be a street urchin who has been surviving on her own in the slums of a major city in Remnant. When she meets the RWBY team, she initially distrusts them but eventually becomes an important part of their group. Also, a grizzled old veteran of many battles against Grimm could be added. He could be a mentor figure, teaching the RWBY characters new combat techniques and sharing his wisdom about the history of Remnant and the Grimm.
There could also be a group of street - smart kids who befriend the Baudelaires. They have their own set of skills and stories, and together they can form a sort of alliance to protect their neighborhood from any potential threats. These new characters would bring in fresh perspectives and interactions for the existing characters in the fanfic.
You could add a young and inexperienced vault hunter who is eager to make a name for themselves. They might start off as a bit of a nuisance to the more experienced characters but gradually prove their worth. There could also be a mysterious merchant who is not what they seem. They might have a hidden agenda and be involved in some sort of illegal trading that could have a big impact on the Borderlands economy.
An old - fashioned Pokemon breeder who has a deep connection with the traditional ways of raising Pokemon. They could provide the main characters with valuable advice on how to make their Pokemon stronger and healthier. However, they might also be a bit stubborn about sticking to the old ways and this could cause some conflicts with the more modern - thinking characters in the fanfic.
A healer who was a friend of Lily's could be introduced. This healer could have some special knowledge about the magic that Lily used to protect Harry, and could help Harry understand more about his mother's abilities.
A new young teacher at Hogwarts. She could be a prodigy in Transfiguration, having mastered some really advanced spells at a young age. She brings a fresh perspective to teaching and has a bit of a rivalry with McGonagall in the fanfic. She might also have a mysterious past that is gradually revealed throughout the story.
A young mage who has the power to communicate with all types of magical creatures, not just dragons. This mage could be a valuable ally or a source of trouble for the existing characters in the fanfic.