Loki could also show signs of fear, though he would try to hide it. Inside, he knows the power that Thanos wields. But on the outside, he would maintain a facade of bravado. His reactions would be a mix of his natural cunning and the instinct to survive in a very dangerous situation.
Another tip is to look for fanfictions written by well - known and respected authors in the Loki or Marvel fanfiction community. They are more likely to write engaging stories about Loki kidnapping scenarios. You can usually find lists of popular authors on the fanfiction platforms as well.
Another scenario could be that Loki forms an unexpected alliance while in captivity. He could meet some other captives who have a grudge against Thanos. Together, they could plot against Thanos from the inside. Loki's silver tongue might be able to convince these captives to trust him and follow his lead. They could create a distraction or a mutiny within Thanos' forces, which would give Loki an opportunity to either escape or turn the tables on Thanos.
Well, if Harry Potter was kidnapped by Loki, it could be a total chaos. Loki might use Harry's magic for his own devious plans. Maybe he wants to take over Hogwarts using Harry's knowledge of the school's secrets. Or he could be trying to trade Harry for something valuable in the wizarding world. Another possibility is that Harry would try to outwit Loki with his own brand of cleverness and magic, leading to a battle of wits between the two.
At the beginning, Harry would be frightened. He's in an unknown place with Loki, who is known for his trickery. But Harry is no pushover. He would quickly gather his courage. He would remember all the times he's faced danger at Hogwarts. He might try to communicate with Loki to understand his motives. If Loki reveals that he wants to use Harry's magic for something, Harry would try to find a way to outsmart Loki. He could pretend to cooperate while actually looking for a weakness in Loki's plan. Harry would also be thinking about his friends at Hogwarts and how he needs to get back to them, which would give him extra motivation to fight back against Loki.
The OC might find themselves in a really strange situation. Loki could be using the OC as a pawn in a bigger scheme against the Avengers. He might try to use the OC to get some valuable information or as a bargaining chip. The OC, on the other hand, could be trying to outwit Loki, using their own wits and any knowledge they have of the Avengers' world. It would be a battle of intelligence between the OC and Loki.
The OC might be terrified at first. After all, being kidnapped by Loki is no joke. But they could also quickly gather their courage. Maybe they would try to talk to Loki, to understand his motives. If the OC is smart, they would know that Loki has his own reasons for doing things and might be able to find a way to reason with him.
The Order of the Phoenix would immediately spring into action. They would start searching for Harry using all their magical resources, including spells like the Tracking Charm. Dumbledore would likely be at the forefront, using his vast knowledge and connections to try and figure out where Loki has taken Harry.