In the 'shield tris to kidnap harry fanfiction', Shield Tris could be acting out of jealousy. Harry might be getting all the attention and glory in the wizarding world, and she feels left out. So, she decides to kidnap him to bring him down a notch. Or, she could be in a desperate situation herself, like being blackmailed by a more powerful and evil force. To save herself, she has to kidnap Harry as per their demands.
Well, perhaps in this fanfiction, Shield Tris is being misinformed. She might believe that Harry is in possession of something extremely valuable, like a powerful magical artifact. So, in her mind, kidnapping Harry is the only way to get that item. It could also be that she's part of a group that has a radical ideology and they see Harry as a threat to their plans, so they order her to kidnap him.
In this fanfiction, Harry's reaction could be a mix of fear and determination. He has faced many dangerous situations before, but being kidnapped is a new threat. He might initially be afraid, but then his Gryffindor courage kicks in. He could try to outwit Shield Tris. Maybe he pretends to be compliant at first, but then uses a clever spell or trick to turn the tables on her. He could also try to use his knowledge of the wizarding world and its hidden passages to evade her.
Fury might want to use the 'OP' character's powers for his own gain. Maybe he wants to use their magic to achieve something in his own world or plans.
Maybe he wants to use Ichigo as a bargaining chip. If there are other forces or characters in the fanfiction world that Kisshu is in conflict with, he could kidnap Ichigo to gain an advantage over them. For example, if there are rival groups vying for power or resources, Ichigo might be valuable to them in some way, and Kisshu could use her to negotiate. Another motive could be that he believes Ichigo has some sort of special power or knowledge that he wants to extract from her, and kidnapping is his way of getting close enough to do so.
One possible motive could be protection. Annabeth might think that there is a threat to Percy that she can only handle by taking him away from the situation. For example, if there's a prophecy that puts Percy in danger and she believes she can keep him safe in a hidden location.
Maybe Sirius wants to train Harry himself. In fanfiction, he could believe that he has a better understanding of the Dark Arts and how to fight Voldemort compared to the professors at Hogwarts. So, he kidnaps Harry to start his own special training regime away from the school.
Love could be a strong motive. If Tobias has feelings for Tris, he would naturally want to protect her from harm, especially from someone like Peter who might be a bully or a threat.
One possible motive could be a misunderstanding. Maybe Steve believes Tony has done something that endangers the team or the world, but he's misinformed. Another could be that Steve has been mind - controlled. In some fanfictions, external forces take over Steve's mind and make him do things he wouldn't normally do, like kidnapping Tony.
It could also be for power. In the fanfiction world, Sebastian might think that by kidnapping Kurt, he can gain some sort of power over the New Directions or the McKinley High glee club. He might want to use Kurt as a bargaining chip to get what he wants from them.
Another motive could be related to some sort of power play. Eric might want to use Sookie as a bargaining chip. Since Sookie has her special abilities, other powerful entities in the fanfiction world might be interested in her. Eric could kidnap her to gain an advantage over his rivals.
Maybe in the fanfiction, Naruto is being controlled by some dark magic or a powerful enemy. This could force him to kidnap Lemon against his will.