Hermione could be a great magical guardian in fanfiction. She's smart and resourceful. With her vast knowledge of magic, she could protect Harry in many ways, like using her spell - casting skills to fend off dark wizards.
Dumbledore, in some alternative fanfiction scenarios, could be a more active magical guardian. He could use his wisdom and powerful magic not just from behind the scenes but be right by Harry's side. He might teach Harry more directly about his destiny and how to face Voldemort with even greater strength.
A potential guardian could be Sirius Black's spirit. Even though he died, his love for Harry could be so strong that it allows his spirit to act as a guardian. He could appear to Harry in times of need, give him advice, and even use his limited spectral powers to protect Harry from minor threats.
Perhaps Sirius Black could be Harry's magical guardian instead. In the original story, Sirius had a strong connection to Harry and a great desire to protect him. Even though Dumbledore was a major figure in Harry's life, Sirius was his godfather and had a natural claim to the role of guardian.
It could be his mother, Lily. Her love was already a powerful protection for Harry, so in the fanfiction, it could be her spirit acting as a guardian angel, using her love to shield him from harm in a more direct and continuous way.
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.
Lily Potter could also be a great candidate. Her love for Harry was so strong. As a guardian angel, she could appear to Harry in his dreams or in moments of great danger, using her motherly love as a shield and giving him advice based on her own experiences in the wizarding world.
Sakura could be a great guardian in a 'naruto guardian fanfic'. She has strong medical skills and combat abilities. She could use her medical ninjutsu to heal Naruto when he is injured in battles and also fight alongside him, protecting him from harm.
Another possibility is that the heiress could be a new character entirely, created by the fanfiction author. She could be from a foreign wizarding family that has a claim to something in the British wizarding world. This new character could bring in different cultural elements of magic and challenge the traditional ways of the Hogwarts - centered wizarding society.
A centaur could also be the Guardian of Magic. Centaurs are known for their wisdom and connection to nature. They might see it as their duty to protect magic from being misused by humans. In the fanfiction, the centaur - guardian could use their knowledge of the stars and natural magic to combat the dark wizards.
Well, in some 'Magical Guardian Harry Potter Fanfiction', one interesting concept could be the unique magical abilities of the guardians. For example, they might have powers that are a combination of different Hogwarts houses' traits. They could be extremely loyal like a Hufflepuff, yet brave as a Gryffindor when protecting Harry.
Another possibility is a reformed dark wizard. Someone who has seen the error of their ways and now uses their in - depth knowledge of dark magic to teach students how to defend against it. This character would have a very interesting backstory, having once been on the wrong side but now using their experiences to help the next generation of wizards in the DADA class.