They could be very traditional and strict pure - blood wizards. Maybe they were part of some ancient magical order and had high expectations for the Potter family. They might be disappointed in how James and Lily Potter deviated from some of the old ways, but be very proud of Harry when they get to know him.
Perhaps his grandparents were great adventurers in their time. They could have traveled to far - off magical lands and encountered strange and wonderful things. Their experiences could be passed on to Harry, inspiring him to explore more of the wizarding world and its secrets. They might also have been involved in some great battles in the past, and their war stories could give Harry valuable lessons for his own fight against Voldemort.
If Harry Potter meets his grandparents in a fanfic, it could be a life - changing encounter. His grandparents would likely be shocked and overjoyed to see him. They might be able to fill in the gaps in his knowledge about his family history. They could have known some secrets about the prophecy related to Harry and Voldemort that could help him better understand his destiny. They might also be powerful wizards or witches in their own right and offer to train Harry further in magic, especially in areas that Dumbledore or other Hogwarts professors hadn't covered. Their presence could also give Harry a sense of belonging and family that he had been missing all his life.
Perhaps in the fanfiction, Harry discovers that his grandparents had a hidden magical legacy. They had been working on a powerful charm to protect the Potter family long before Harry was born. Harry finds clues about this charm and with the help of his friends, he tries to complete it, believing it could be the key to finally defeating Voldemort.
One possibility is that Harry's grandparents help him uncover his family's true history. They could show him old family portraits and explain the relationships and events that led to the present situation. His grandparents may also have a different perspective on the fight against the dark forces. They could advise Harry on how to use his powers more effectively and how to build alliances. And they might even be the ones to finally reveal the full story behind the prophecy related to him.
In this fanfiction, his grandparents might be described as having a deep connection to the magical land they live in. They could be the keepers of ancient family secrets. Their physical features might be aged but still show signs of the great beauty and strength they had in their youth. And they may be very loving towards Harry, making up for the lost time they could have had with him.
One interesting 'Harry Potter Grandparents' fanfiction could be one where Harry discovers hidden secrets about his grandparents through a magical diary. It might show his grandparents' adventures at Hogwarts when they were young and how those events shaped the Potter family legacy.
In this kind of fanfiction, perhaps Harry would grow up with a different kind of family warmth. His grandparents might be more traditional and instill in him values that are different from what he would have learned at the Dursleys. He could be more connected to the wizarding world's history as his grandparents might have more stories to tell from the older days. Maybe he would be less bullied and more confident, and his magical abilities could develop in a more natural and unrestrained way.
They could have had adventures in ancient magical ruins. For example, they might have explored a long - lost wizarding temple filled with powerful spells and dangerous traps. They could have fought off dark creatures guarding the secrets within.
If Harry Potter's grandparents read fanfiction, they might have mixed feelings. On one hand, they could enjoy seeing the continued love for the wizarding world they were part of. But on the other, they might find some of the modern interpretations a bit too out - there. They were from a more traditional wizarding background, and fanfiction can be full of modern ideas and concepts that could seem strange to them.
He might be more old - fashioned in his ways. His grandparents' values would likely have a big influence on him, so he could be more reserved and traditional compared to the Harry we know from the original series.