He could be married to Luna Lovegood. Their relationship in the original series was more of a friendship, but in fanfiction, it could be that they got married. Maybe they were on an adventure together, something went wrong magically, and they woke up married. Luna's unique personality would bring a lot of interesting elements to the story as they figure out their new relationship.
One popular 'Harry wakes up married' fanfiction might involve him waking up married to Hermione. In this scenario, they could have been under the influence of a magical spell that made them get married without realizing it. Then they have to deal with the consequences, like telling their friends and trying to figure out if they actually have feelings for each other.
Harry would probably be shocked and a bit suspicious at first. He'd wonder if Draco had some underhanded plan. Ron, on the other hand, would likely be outraged. He's always had a bit of a rivalry with Draco and the thought of Hermione being married to him would be hard for him to accept. Ginny might be more open - minded and try to figure out what really happened.
One possibility could be a spell gone wrong. Maybe some dark magic or a misfired charm during a chaotic event in the wizarding world caused their minds to be altered and they unknowingly got married. Another idea is that it was part of a devious plot by someone who wanted to stir up trouble between Gryffindor and Slytherin. It could also be a result of a strange magical contract that they were unknowingly part of.
Perhaps there are challenges from their friends and the wizarding community. Some might be shocked or disapproving of their union. This could lead to them having to defend their relationship and face various social pressures. Maybe they have to work together to prove that their marriage can work despite the unorthodox start.
Well, in fanfiction, it could be really interesting. Harry might first try to figure out where he is. Since he's in Vegas, he could encounter all sorts of muggle things like slot machines and big shows. He might use his magic by accident and cause a stir among the muggles. And then he'd probably start looking for a way to get back to his own world, either by trying to find some kind of magical object or by using his own magic in a new and creative way.
Hermione would likely be a key friend. She might be initially very confused and try to analyze the situation rationally. She could be worried about how this will affect Harry and his future, and might try to find a way to reverse the situation if it seems harmful to Harry.
Jie, Su Xing, and Li Wei's relationship originated from the fact that they were all artists under Sky Entertainment. When Li Wei participated in the Fast Men's Competition, Su Xing had performed on the same stage as him as a guest singer. However, the news of Su Xing beating Li Wei was later exposed. The reason was that Li Wei had an intimate relationship with Su Xing's girlfriend. According to netizens, Jie had closed the door backstage when he woke up to beat Li Wei. This incident affected Su Xing and Li Wei's careers, while Jie was praised and promoted because of his actions. As for why Jie was no longer in the same frame as Su Xing, it was probably because this incident had caused their relationship to become awkward.
Another possibility is that Harry ends up married to a Muggle he meets in Vegas. This would be really interesting as he has to navigate the differences between the wizarding world and the Muggle world while being married to someone who has no idea about magic at first. It would be a story of discovery and adjustment for both Harry and his new spouse.
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.