Harry might also be cautious. He knows the Malfoys are sly and not to be trusted easily. So he would be careful with his words and actions, not wanting to give them any advantage or opportunity to cause trouble for him or his friends.
Harry might be angry and defensive. After all the past encounters with the Malfoys, he'd be ready for more of their nastiness.
Well, it could go a few ways. One possibility is that the Malfoys would start their typical taunting of Harry. Lucius might look down on Harry with disdain and make some veiled threats. Narcissa, on the other hand, could be a bit more reserved. Harry, being Harry, would likely respond with his own brand of courage. He might even try to use the situation to gain some information about the Malfoys' recent activities if he suspected they were up to no good.
In the fanfic, it might lead to a tense confrontation. Harry could feel anger towards the Malfoys as they are known for their prejudice. Draco might taunt Harry as usual, and Lucius Malfoy could look down on Harry with his typical haughty attitude.
He could be shocked. After all, he may have thought his parents were long gone or never expected to meet them.
Well, one possible plot development could be that the Malfoys, in rescuing Harry, have a change of heart towards the whole fight against Voldemort. Maybe they start to see the error of their ways and side with Harry more openly. For example, they could use their influence in the wizarding world to help Harry gather more allies.
He could also be shocked into momentary silence. His first sight of Harry might bring back a flood of memories, both good and bad. Maybe he freezes for a second, his mind racing with thoughts of Lily, Harry's mother, and how things could have been different. Then he quickly composes himself and tries to hide his inner turmoil behind his usual stern facade.
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.
Adrien could be so amazed that he freezes for a moment. Then, he might compliment Marinette on her singing. This could lead to a deeper conversation between them, as he asks her about why she was singing and if she has any other hidden talents.
They could be skeptical. They might wonder if Jaden has good intentions towards Alexis. So they could be a bit cold at first, observing Jaden closely and waiting to see how he behaves. This would put Jaden in a tough spot, having to work hard to win them over.
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.