Eric might also use his position of authority. If he's in a position of power within the story's setting, he could simply order Peter to stop. For example, if Peter is violating some rules of the group or faction they belong to, Eric could threaten him with punishment if he doesn't let Tris go.
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.
Well, Geralt might die as a result of a powerful curse or magic. Maybe he angered a powerful sorcerer or witch who cast a spell on him that he couldn't resist. This could be a slow and agonizing death as the magic takes its toll on his body and mind. Another possibility is that he sacrifices himself for someone he loves or to save the world from a great evil. He might put himself in harm's way knowingly, and in the process, lose his life.
Superman's death in comics is often a result of epic battles or selfless acts. For instance, he might face an opponent whose power is just too overwhelming, or he might give his life to prevent a major catastrophe.
Gwen's death in the comics is often a result of a tragic and complex event. Usually, it involves a confrontation with a powerful villain or a series of unfortunate circumstances.
Well, Loki's comic deaths aren't straightforward. It could be as a result of clashes with other superheroes or from cosmic events that he gets caught up in. The circumstances change from one comic series to another.