Maybe he'll be looking for a magical destination. He could be seeking a place to find new magical creatures or study ancient magic. The travel agent might offer him a trip to a hidden wizarding village in the Alps, full of unique spells and potions.
In the fanfiction, Harry Potter going to a travel agent could lead to an adventure. The agent might recommend a journey to an uncharted magical island. There, Harry could discover lost magic and perhaps face some new dark forces. He might also meet new allies along the way who help him on his journey.
He might meet some interesting characters there. Maybe he'll encounter a famous tennis player who gives him some tips on the sport.
Well, in fanfiction, when Harry goes alone to the ball, he could end up being the center of attention in an unexpected way. Since he's alone, people might be curious about him. He might also use this time alone to observe the other characters more closely, learning secrets or motives that he wouldn't have noticed if he was with friends. And who knows, he could start a new trend of going solo to the ball, making others think it's a cool and independent thing to do.
He might encounter some strange magical creatures that are only found underground. For example, there could be a new type of goblin or a magical mole with special powers.
He could encounter a new magical creature. The goblins at Gringotts are known to have various magical creatures guarding different vaults. Maybe Harry comes across a rare and friendly creature that helps him on his journey. For example, a small fire - breathing dragon that he befriends and it later aids him in a battle against Voldemort's forces.
Well, they might find it really interesting. They could discover new perspectives on the characters. Maybe they'll start to see Harry and his friends in a different light, and it could even change their views on the Gryffindor - Slytherin rivalry a bit.
Well, he might be tempted by the dark magic within the Horcrux. It could try to manipulate him, maybe show him false visions of power or ways to defeat Voldemort that are actually leading him astray.
In fanfiction, he could discover a long - lost family vault. It might be filled with ancient artifacts and powerful magic items that could help him in his fight against Voldemort.
He might meet some strange magical creatures there that are used for experimental treatments.
In some fanfictions, when Harry Potter goes through the mirror, he might find himself in a parallel magical world. This world could have different versions of his friends and enemies, and he may have to face new challenges to find his way back to his own world.
In the fanfiction, Snape could be in a really tough situation when Harry comes to him for help. On one hand, he has his loyalty to the Dark Lord (or at least that's what others think), and on the other, there's this boy who is the son of the woman he loved. He might end up guiding Harry in a very roundabout way, like giving him a potion ingredient that has a hidden meaning or leading him to a certain book in the library that contains the solution to Harry's problem.