He may be confused at first. Fanfics can be very different from his real experiences. He might wonder why people write such things about him and his world.
Well, Harry Potter is a rather humble character. He might initially feel a bit embarrassed to see himself as the center of so many fictional stories created by fans. If the fanfic portrays him as a hero in new adventures, he would probably be honored. However, if it misrepresents his friends or the values he holds dear, he could be a bit indignant. He would likely approach it with an open mind but also with a sense of protectiveness towards his own story and those he loves.
There's a chance he'd be inspired. The stories of the Naruto characters' determination and growth in the fanfiction could stir something in him. He might think about his own journey as a wizard and how he can further develop his skills and character, taking cues from the Naruto characters' tenacity.
Perhaps the travel agent is a bit of a troublemaker. Instead of suggesting normal wizarding travel destinations, they might try to persuade Harry to visit some off - limit or even illegal magical places. They could tell him about a secret portal to a dimension where dark magic is still being practiced freely, which of course, Harry would have to resist.
Hermione would probably be both curious and worried. She'd want to research all about Harry's half - demon nature to find out what it means and how to help him. Ron, on the other hand, might be a bit more hesitant at first. He might be a bit scared but would eventually come around because of his loyalty to Harry.
Some of them would be entertained. Iron Man might laugh at the strange spells and potions. Hulk might not understand much but could enjoy the action parts if there are any. Thor could be curious about the magic and how it compares to his Asgardian powers.
The Avengers' reaction would be a mix of caution and curiosity. Hawkeye might keep his arrow aimed at Harry, ready for any sudden moves. Black Widow would be using her skills to read Harry's body language and try to figure out if he's lying. The Hulk might be held back initially, but if Harry made any sudden or 'threatening' moves, things could get really hairy. Overall, they'd all be on high alert until they understood that Harry was not an enemy but a young wizard with his own set of skills and a good heart.