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.
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.
In this scenario, it could also lead to a major shift in the relationships within the fanfiction. Hermione might feel betrayed if Draco doesn't stand up to his father. And Draco could be forced to make a difficult choice between his family's expectations and his feelings for Hermione. Lucius's interference could also bring in other elements of the wizarding world, like the Ministry or other pure - blood families getting involved depending on how the situation unfolds.
Well, depending on the context of the fanfiction, Sirius could also be very understanding. If he knew that Harry and Hermione were just having a private conversation about important matters like their fight against Voldemort or schoolwork, he might just give them a knowing smile and say something like 'Carry on, then. Just making sure everything's all right.' He's a rather perceptive character, after all. And he trusts Harry a great deal, so he would likely give them the benefit of the doubt before assuming anything untoward.
He might be shocked. Draco has always seen Harry as an equal rival in some ways, but finding out he is Lord Black means Harry has a whole new level of status. So, shock is a very likely initial reaction.
Draco may initially react with disbelief. But as he realizes it's true, he could have a complex range of emotions. He might be disgusted by the act itself. His Slytherin nature might make him want to be cunning in dealing with the situation, perhaps by finding out more about the incident in a secretive way. He could also have a moment of self - reflection, thinking about how his own actions in the past might have added to Harry's stress or made him more vulnerable. And ultimately, he could be motivated to help Harry heal, whether it's through emotional support or taking more practical steps like helping him report the crime if that's applicable in the fanfiction world.
If Lucius walks in, the power dynamic between Harry and Draco would likely shift. They would no longer be in their own little world and would have to deal with an adult authority figure. Draco might become more submissive to his father's commands, and Harry would have to face the wrath of Lucius, which could put him in a very difficult situation.
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.
It could involve Harry having some sort of dark power or being under a dark influence that leads him to enslave them. Maybe he discovers a long - forgotten spell or artifact that gives him this power.
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.