There is a difference between Superhero comic book characters and the kinds of characters found in more traditional storytelling.  The difference is that comic book characters are infinitely malleable.  There is no limit to the degree to which comic book characters can have things happen to them that may negatively impact their character.  But there is always the possibility, if required by the author, that these negative changes can be reversed. 

Almost everything that is external to the character can change, be destroyed, and subsequently be restored.  This is most obvious in the comic book trope, Not Really Dead, where a character is actually killed in a particular storyline, only to re-appear later and they're completely fine.  And it is up to the pleasure of the writer as to whether we get an elaborate explanation of their resurrection or if it is simply passed off without comment.

What cannot change, however, is their style and attitude.  Deadpool or Ironman are both irreverent, wisecracking, anti-authoritarian heroes, and this attitude is as much a part of their character as the more narrative sense in which characters are developed.

Traditional characters are developed through the events that happen to them throughout their lives, and the choices they make when presented with these crises.  For a comic book character, these choices almost don't matter, unless they are necessary to the plot, and then only temporarily.  For a traditional character, the choices made in pivotal moments literally define who they are ever after.  Frodo decides to take the ring, Faramir decides not to take it from Frodo.  These milestones are reflections of who the character is, and also where the character development goes from that point in their lives onward.  

In contrast, the actual choices Comic Book characters make are entirely irrelevant to their character, as long as they make these choices with the appropriate attitude.  Fighting and conflict are classic examples of this.  When Thor fights the Hulk, the outcome is entirely meaningless.  The audience has no expectation that the outcome will have any impact on either of these characters development or trajectory.  Neither of them will actually die as a result of the encounter.  The only impact is on the swagger and attitude that they temporarily project during and after the event.  The event is important because it highlights the differing strengths, tactics, and fighting styles of the two heroes.  

Should a seemingly longer ranging outcome occur, for example if Odin is blinded, it won't have any long term impact on the character, but it might represent a short-term change that causes a temporary imbalance.  And it is through these temporary changes that short run series are created.  The end of a series is usually represented in a return to the status quo.  When Odin loses an eye, it does not meaningfully limit his actual eyesight.  When Thor loses an eye, Rocket makes him a new one.  

Sometimes a comic book state change does occur.  These changes allow the writers to explore the attitude of the character from a different perspective. For example, Odin has gone on to Valhalla and Thor has taken his place, representing a state change in the universe. But if the writers should need to see Odin return, the audience would not be surprised if he made an appearance.