Mastery of special powers or skills. In the case of Doctor Strange, his magical abilities make him one of the most powerful in the Marvel universe. He can manipulate time, space, and dimensions, which gives him an upper hand in any situation. So, a human in fiction can be the strongest through the possession of such extraordinary skills.
Goku from Dragon Ball is also a strong contender. He has achieved various levels of super - saiyan forms which give him incredible strength, speed, and energy - based attacks. His power levels are off the charts and he has saved the universe multiple times with his might.
One reason could be the unique take on the character Issei. In this fanfiction, it might explore his growth in a different way compared to the original source. It could give him more human - like qualities that make readers connect with him on a deeper level.
Power is a big factor. For example, characters like Thor in the Marvel universe have god - like powers. They can control lightning, are super strong, and have great durability. Their powers put them at a very high level among fictional characters.
Power levels often play a big part. For example, if a character can control time or manipulate reality like Scarlet Witch in the Marvel Universe, that's an incredibly powerful ability. They can rewrite the rules of existence, which gives them a huge advantage over others.
Experience and mental fortitude play significant roles. A swordsman who has faced numerous challenges and adversaries, like Aragorn from The Lord of the Rings, is stronger for it. Aragorn has fought in many battles, and his experience gives him the confidence and knowledge to handle different situations. His unwavering resolve in the face of danger and his sense of honor also make him a great swordsman. He doesn't just rely on physical strength but also on his mental and emotional stability during combat.
Power levels are a big factor. For example, if a character can destroy planets with ease like some of the powerful beings in science - fiction, that's a sign of great strength. Also, invulnerability plays a role. A being that can't be hurt easily is stronger than one that can be easily defeated.
Raw power is a big factor. If a character can effortlessly destroy planets or move mountains, like Galactus in Marvel Comics, that's a sign of great strength. He can devour entire planets to sustain himself, which shows his extreme power.
The strength of a werewolf in fiction can also be related to its origin. If a werewolf was created through some ancient and powerful magic or curse, it might inherit greater powers. For instance, in some stories, werewolves born from a specific bloodline might have special abilities like telepathy among their kind or the ability to see in complete darkness. Their social status within the werewolf community, such as being an Alpha or having a large pack following, can also boost their strength as they can draw on the collective power of the pack and have others to support them in fights.
Power and abilities play a huge role. For example, if a character can manipulate time like Doctor Strange in the Marvel Universe, that gives them an edge. They can stop time, reverse events, or see into the future to outwit their enemies.
I think it's a combination of different aspects. First, physical strength is important. Characters like the Hulk have incredible physical strength that allows them to overpower most opponents. Second, special abilities matter. A character like Scarlet Witch with her reality - warping powers is extremely formidable. And finally, the character's ability to grow and overcome challenges. A character who can constantly evolve like Naruto, from being a weak ninja to one of the most powerful, can be considered strong in the world of fiction.