Reactions could vary greatly. Some might freeze in panic, while others might try to explain or make excuses. But in any case, it's a highly stressful and embarrassing moment.
This kind of content is not appropriate and goes against common decency. We should focus on positive and meaningful subjects instead.
One possible reaction could be shock. Carlisle might be momentarily stunned to see them in an unexpected situation. He could quickly compose himself and offer some words of wisdom or caution. For example, he might remind Edward to be extra careful with Bella considering her human nature.
Another possibility is that Lucius could be initially confused. He might not understand what he's seeing at first. After all, Harry and Draco are supposed to be enemies in the general wizarding world view. He could stand there for a moment, trying to process what's going on before taking any action.
Sirius may also be angry at first. Given his protective nature towards Harry, if he misinterprets the situation as Draco causing trouble for Harry, he would likely step in assertively. But if it's a situation where Harry and Draco have a more positive or friendly interaction in the fanfiction, Sirius would have to re - evaluate his initial reaction.
She might be shocked at first. Then she could try to have an open and honest conversation with her daughter about privacy and appropriate behavior.
She could also be angry. If she has strong values about propriety and public behavior, she might scold the woman for doing something so inappropriate in public.
One possible reaction of Sirius could be shock. He might stand there frozen for a moment, unable to believe what he's seeing. Another reaction could be anger. If Sirius has certain expectations or feelings about James and Regulus' relationship, he could get angry at finding them together. Or he could be confused, trying to figure out how and why this is happening between his friend James and his brother Regulus.
Well, Ron could get angry. He has a strong loyalty to Harry, and seeing Harry with Draco, who he has always seen as an enemy, might make him feel betrayed. He might immediately jump to conclusions and start shouting or demanding an explanation from Harry.
She might be a bit shocked at first. But then, being Sally, she'd probably quickly regain her composure and give them a knowing smile. After all, she's seen Percy grow up and she would be happy for him to have such a close relationship with Annabeth.
Well, it depends on the story. Maybe she discovers a big mess that the kids made and she gets really angry. For example, if it's a story about a party the kids had while she was out, she might find broken cups and spilled drinks everywhere.