His best friends, Ron and Hermione, are most likely to come to his rescue. They've been through so much together and would never abandon Harry. Ron would bring his loyalty and courage, while Hermione would use her brains and magic skills. Also, Dumbledore or other powerful wizards from Hogwarts could step in. Dumbledore, with his great wisdom and powerful magic, would surely not let Harry be in the hands of a vampire for long.
The Order of the Phoenix members might be involved in rescuing Harry. They are a group dedicated to fighting against the dark forces. Sirius Black, if he was still alive in the fanfic, would be very eager to save Harry. He has a strong bond with Harry as his godfather. Additionally, some of the magical creatures that Harry has befriended in the past, like the centaurs or the hippogriffs, could also play a role in his rescue. They might use their unique abilities to help find and free Harry.
Her friends could also play a crucial role. If she has a group of loyal friends, they might band together to find her. They could use their knowledge of the area where she was last seen or any clues they can gather to track down the kidnappers and save her.
Naruto would be a likely candidate. He has a deep bond with Sakura and would never let her be in danger for long. He'd probably rush in without hesitation to save her.
Annabeth could be the one to come to Percy's rescue. She is very intelligent and resourceful. She might figure out Gaea's weaknesses and use that knowledge to free Percy.
Maybe Pepper Potts could find out what Tony has done and rescue Peter. She might be able to talk some sense into Tony and make him release Peter.
It could be Nightwing. He was once Robin himself and has a special connection to the current Robin. Nightwing might hear about the kidnapping and step in to save Robin, using his own unique fighting style and experience.
His friends like Kuwabara and Kurama might also join in the rescue. Kuwabara with his tough fighting spirit and Kurama with his cunning and powerful abilities could be a great help in getting Keiko back from Toguro.
There's also a possibility that Hinata's own clan, the Hyuga, would take matters into their own hands. They have their own unique techniques and a sense of pride. They would not allow the Akatsuki to keep one of their own captive for long and would send their strongest members to retrieve Hinata.
They might start by gathering information. Harry could use his invisibility cloak to sneak around and eavesdrop on potential suspects. Ron would probably try to contact his brothers who have connections in different parts of the wizarding world for any leads.
Alec might also come to her rescue. As a skilled Shadowhunter, he has a strong sense of duty. Plus, he's part of Clary's group, and he wouldn't stand by and let a fellow Shadowhunter be attacked by a demon.
Her father, Charlie, might try to rescue her. He loves Bella deeply and would be very worried when she goes missing. He could start investigating and find out that the Cullens are involved.