Well, in some fanfictions, Naruto might defeat Kisame in a battle and take the sword as a trophy. Maybe he uses his newfound Sage Mode powers or some other advanced jutsu to overpower Kisame and claim the sword.
Kisame would probably be very angry at first. Samehada is his weapon and has been with him for a long time. He might feel betrayed and try to get Samehada back by force.
At first, it would be full of suspicion. Naruto is a Konoha ninja and Kisame is from the Akatsuki. But as the teaching progresses, they might develop a mutual respect. Naruto would respect Kisame's power and knowledge, and Kisame might respect Naruto's determination.
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.