In the fanfic, it could be that Harry wakes up to find Gabrielle in a bit of trouble. Maybe she's lost something in the room and Harry helps her look for it. As they search, they get to know each other better and form a bond. Harry might be reminded of his own experiences with Ginny when he first started getting closer to her.
Well, perhaps they could start the day with a friendly chat over breakfast. Harry might share some of his wizarding world stories with Gabrielle, and she could be really fascinated by them.
New and upcoming writers could also write a great one. They might bring a fresh perspective to the idea. Maybe a young writer who has a vivid imagination and is a big fan of both Harry and Gabrielle as characters. They could come up with unique scenarios and interactions between the two that we haven't seen before.
In the 'beerus wakes up early fanfic', maybe Beerus wakes up early and decides to go on a sudden hunt for the best food in the universe. He could startle the local inhabitants of the planets he visits as he demands the most delicious delicacies.
In this fanfic, Aang might use the extra time to practice his airbending. He could go to a secluded spot and work on new techniques or perfect the ones he already knows.
Well, it could be a story where Harry and Fleur are part of a secret mission together. They had to stay the night in a hidden place for safety. When Harry wakes up with Fleur, they might start discussing their next moves in a very friendly and perhaps a bit flirty way. They could exchange stories about their experiences at Hogwarts and Beauxbatons respectively, and then realize they have more in common than they thought.
Well, he might be really confused at first. GT has a different feel and set of events compared to the normal Dragon Ball universe. He could start looking for strong opponents right away, maybe even mistake some GT characters for threats they're not and cause some chaos.
The human might find themselves in a strange and mysterious underground world filled with unique creatures. Maybe they'll encounter a group of underground dwellers who have their own culture and language, and they'll have to figure out how to communicate and survive among them.
In this kind of fanfiction, Ash might wake up with new Pokemon - like abilities. For example, he could communicate with Pokemon in a more direct and profound way, like understanding their every thought and emotion just by looking at them. He might also find himself physically changed, perhaps having some physical features of a Pokemon, which could lead to all sorts of interesting adventures and interactions with his friends and other Pokemon trainers.
One possible plot could be that the girl is a fellow student at Hogwarts who has fainted during a dangerous situation, like a duel gone wrong in a secret passage. Harry, being the heroic type, uses a spell to wake her up. Then they end up having to work together to get out of the passage before it closes or some other threat arrives.
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.
Well, one possibility is that Ash wakes up with all the powers of Mew. He could then use these powers to quickly become the best Pokémon trainer ever. He might be able to communicate telepathically with all Pokémon, understand their needs and desires instantly, and use his newfound psychic abilities to battle more effectively. For example, he could levitate his Pokémon during battles, giving them an unexpected advantage.