Let's talk a bit about the 2003 Daredevil movie and the Daredevil Netflix series that just came out. The former was largely panned, and is considered one of the low points of the dipping-our-toe-in-this-superhero-thing movies of the early-aughts. The latter is yet another layer on the every-growing current Marvel Cinematic Universe that consists of a dozen films and two other TV series, with several more of both announced for the coming years, and has been widely lauded.
Now, what were the key differences between these two depictions of, fundamentally, the same character? Why did one work, and the other failed?
I would argue a key reason would be Suspension of Disbelief.
The recent iteration, despite existing in a world in which alien invasions, flying men in powered suits and green gamma-ray monsters are an accepted fact of life, maintains a certain degree of real-world believability. Matt Murdock is blind, but his other senses are superhuman, and he's trained himself to use those senses as a highly skilled street fighter. But he's still just a man, and he gets seriously injured along the way over the course of his battles. His skill, his senses and his outright fearlessness allow him to jump up fences and walls, leap from building to building, in ways that would make most parkour enthusiasts' collective jaws drop. But he never transcends "that's amazing" levels of skill. He doesn't do anything that you can't believe a man with sufficient skill and commitment couldn't also do.
Contrast that with the movie version, where Matt leaps off of skyscrapers, using conveniently placed window-washer rigs and telephone cables to jump off of or swing from. As if doing such things at terminal velocity would not be just as fatal as hitting the ground dead on. This from a man who's only superpower is enhanced senses. Even for a "superhero movie", we were given something we just couldn't believe.*
In writing, of course, you have to find that same level of believability, even in a setting where the incredible and fantastic can occur. I struggled with this in early drafts of The Thorn of Dentonhill, where I had Veranix take quite a few heavy beatings and be more or less fine the next day. And I know part of that was going by the Cinematic Flesh Wound Rule**, but my editor called me on that. Unless there's magic healing***, you need to let your characters heal or suffer the consequences. And injuries should have long term consequences if they are bad enough. Thus one of Veranix's injuries went from an arrow straight through his leg to a deep gash from a shot that grazed him. I wanted him hurt, not never walking right again.
This is why the term "Rules of Magic" gets bandied about a lot in genre circles. It's important to establish what fantastic things can occur, so your readers believe the limits you put on your stories. Which presents the inverse problems: when the rules of the fantastic presents an obvious solution, but it simply isn't taken because reasons.****
So: what do you do to balance the believability of your fantastic things?
*- There are actually a host of other reasons why the Daredevil movie didn't work, but this is a big one. Or at least, a symptom of the larger problems.
**- Best illustrated in Last Action Hero, where when Jack Slater is in the "real world" and gets shot, he's on death's door with severe trauma, but once he's brought back into his movie, he can shrug it off.
***- Something which JK Rowling used well, in that magic healing could do a lot, which let her really do horrible things to her characters. Like have Harry's arm-bones be accidentally removed. But it was OK, because a spoonful of Skele-Grow is all it takes to deal with that problem.
****- Also known as the Barry Allen Isn't Too Bright Rule. Because 90% of his cases can be solved by "grab bad guy and put him in my ethically questionable super-prison before he knows what happened".