The character could find a weakness in the orcs' prison, like a loose bar in the cell that they can use to break free.
Perhaps they can befriend an orc who is sympathetic to their plight and help them escape. For example, an orc who has different values from the rest of the tribe and believes in justice might assist the captured human. This could be due to the orc having had a past encounter with a kind human.
One idea could be that the human has a special ability that the orcs want to use for their own gain, like being able to communicate with animals and they hope to use it in battle.
Another way is that he forms an unexpected alliance within Iwa. There could be a dissident group in Iwa who oppose the capture of Naruto. They might help him escape in exchange for some future favor or because they believe in Naruto's cause. Naruto has a way of inspiring people, even those who are initially his enemies, so this is a plausible scenario.
Naruto could use his shadow clones to create distractions. He could make a large number of clones and while the Akatsuki members are dealing with the clones, he could find an opening to escape. Also, he might be able to tap into the power of the Nine - Tails more than ever before in a desperate situation, using its strength to break free from any restraints.
Percy might try to find Voldemort's Horcruxes and destroy them. This would weaken Voldemort and give Percy a better chance to escape. He could also use his demigod speed and agility to outrun Voldemort's spells and find a way out of the dark wizard's lair.
Well, Naruto might escape by using his wits. He could pretend to be compliant with Orochimaru's plans at first, gain Orochimaru's trust a little bit, and then when Orochimaru least expects it, he could make his move. He could also find an ally within Orochimaru's lair. Maybe there's a henchman who has a change of heart and helps Naruto escape. Or, Naruto could discover a weakness in Orochimaru's security system or jutsu that he can exploit to get away.
He could use his Invisibility Cloak. The Avengers might not be able to detect it with their technology. Then he could find a way to apparate out if he's far enough from any anti - apparition charms.
One way could be through alliances. In the Capitol, there might be some people who secretly support her cause or who are simply against the cruel treatment of captives. She could form an alliance with them and plan an escape. For example, a Capitol servant who has access to keys or security codes could help her. Also, Katniss could pretend to be compliant at first, lulling her captors into a false sense of security before making her move.
They could use the Force to overpower their captors. Luke is quite strong in the Force and together with Leia, they might be able to create a distraction and break free.
Percy could use his water powers. He could summon water from nearby sources, like pipes or even the air if it's humid enough. With the water, he could create distractions, like water walls or waves to disorient the Avengers. Then he could make a run for it.
Well, first of all, Percy is a very resourceful character. If he was captured by SHIELD, he'd quickly assess his surroundings. Since he has control over water, he could start by causing a water - related malfunction. For example, if there were any water - cooled systems in the SHIELD facility, he could make them burst. This would create chaos and give him an opportunity to slip away. He could also use his powers to sense any water sources around, like underground water channels. He could then use these as a means of escape, perhaps creating a tunnel of water to swim through. And don't forget his sword, Riptide. He could use it to cut through any barriers or fend off agents if necessary.