He is probably very surprised at first. After all, coming from the wizarding world, being knighted by the Muggle Queen is quite unexpected.
Harry might feel honored. He has always been a humble hero, but this recognition from the Queen makes him realize the far - reaching impact of his actions. He accepts the honor gracefully and sees it as a way to further bridge the gap between the wizarding and Muggle worlds.
Well, it could be that the Queen has a special connection to the wizarding world in this fanfiction. Perhaps she has been secretly informed of Harry's bravery and selflessness all along. And as a symbol of the British monarchy, she knights him to show that the Muggle and wizarding worlds can have a positive relationship. So, she bestows this honor on Harry.
At first, he may be in disbelief. But as he starts to understand what he's seeing, he could become solemn. He realizes the weight of the future and the responsibility he may have to shape it in a positive way. He might also feel a bit of fear, especially if he sees the loss of his friends or loved ones. But overall, his Gryffindor courage would likely kick in, and he'd start to think about how to face whatever the future holds.
He could be shocked at first. Imagine finding out that your whole life has been based on half - truths. He might need some time alone to process it all.
In fanfiction, Harry could react in various ways. He might be curious about this new place. He'd start exploring, looking at all the strange buildings and people. But he'd also be cautious because he doesn't know if there are any threats. He might also try to find other wizards or witches, thinking that there could be some kind of hidden magical community in Vegas. As he explores more, he'd gradually get used to the muggle environment while still trying to figure out how to get back to his normal life in the wizarding world.
In this fanfiction, Harry Potter would interact with the Queen in a very unique way. Since he is used to the hierarchical system in Hogwarts, he would understand the importance of showing deference to the Queen. He could offer her a magical gift, like a charm that gives good luck. And the Queen, being curious, might ask him about his world. Harry would have to be careful not to reveal too much about the wizarding world to the muggles, but still satisfy her curiosity. There could be some misunderstandings too, for example, when Harry tries to explain some magic concepts using wizarding terms that the Queen doesn't understand.
Some might be in shock. After all, Harry has been such an important figure in the wizarding world for so long. His friends like Hermione and Ron would probably be very worried about him and try to find out where he went. The Ministry of Magic could be in a panic, fearing that without Harry, they'll be vulnerable to new threats.
He might be very confused at first. After all, it's a completely new and unexpected situation.
He might be extremely hurt. Harry could go into a state of shock and disbelief at first. He may isolate himself, not wanting to trust anyone else for a while.
Maybe Dumbledore, if he were still alive in the fanfiction. Dumbledore was highly respected and had a great influence. Knighting Harry would be a way for him to publicly recognize Harry's achievements and heroism on a grand scale.
Well, in many such fanfictions, Harry might be shocked at first. He probably feels a sense of pity for Draco too. After all, being under the Imperius Curse means Draco has no control over his actions.