Their friends in Gryffindor might be quite shocked at first. Ron, being Harry's best friend, would probably be a bit angry and concerned. He'd lecture Harry about setting a bad example. Hermione would be more worried about the consequences, like if they got caught by the teachers. Neville might be a bit more understanding, having had his own experiences of growing and making mistakes. Luna would probably just smile and say something really off - the - wall like 'Oh, the drunk stars are making you do interesting things.'
It could be that they are on a mission together and get poisoned by some magical substance that has the side effect of making them drunk. In their inebriated state, they start reminiscing about their past, from their first meetings to their first kisses. This trip down memory lane makes them realize how much they truly love each other and how far they've come as a couple.
In many fanfictions, if Harry and Ginny get caught, it could lead to various outcomes. Maybe they get caught by Hermione who scolds them for being reckless. For example, if they were sneaking around Hogwarts after curfew and got caught by her, she might give them a long lecture about following the rules.
They might face some embarrassment. For example, if they were caught in a private moment, they could be teased by their friends. It could also lead to some misunderstandings among their peers. Maybe others would misinterpret their relationship or the situation they were in.
The main characters are obviously Harry and Ginny. Harry Potter, the famous wizard who defeated Voldemort, and Ginny Weasley, a brave and talented witch. They have a long - standing relationship in the Harry Potter series, and in the fanfiction about their engagement, they are the central focus as they take the next step in their relationship.
One possible plot twist could be that while drunk, they accidentally reveal secrets they've been keeping from each other. For example, Ginny might let slip about a small insecurity she has in their relationship that she's been hiding. Another could be that they end up in a part of Hogwarts they've never been to before while drunk and discover something mysterious, like an old hidden room with strange artifacts. Maybe they also get into a bit of trouble with the school authorities when they are found drunk, but this incident actually brings them closer as they face the consequences together.
In some 'ginny gets drunk fanfiction', the plot might revolve around Ginny being in a new and unfamiliar environment where she gets drunk. This could lead to her exploring a different side of herself. She might meet new people and form new relationships while in this state. The story could then be about how this one drunken night changes her perspective on certain things or people in her life. It could also show her growth as a character as she learns from the experience of getting drunk and the events that follow.
I'm not sure about a specific 'Harry Ginny drunk' fanfic, but you could try searching on popular fanfic websites like Fanfiction.net or Archive of Our Own. Look for tags related to Harry Potter, Harry, Ginny, and 'drunk' to narrow down your search.
They might use their combined magical skills. Harry is known for his powerful Patronus charm, and Ginny is a very talented witch. They could use these skills to fight off whatever is causing the trouble.