And that finally leads to today's topic: Retcons.
You see, ongoing series tend to develop a continuity - some more then others, but still.
Continuity is an important part of ongoin story-telling. It puts events in order and establishes them as part of the overall background-story. When you have long-running stories like Batman, Spider-Man, Grenn Lantern, Flash, Doctor Eho or many many more, which are around for for decades, it can get confusing for new people joining the story, which is why sometimes reboots are happening.
Reboots can be okay, since they are meant to make things more comprehensible for newcomers by ignoring establising a new Origin or a sometimes a new status quo.
Some people like it,some people don't. I think, it depends on the matter at hand: rebooting the Spider? Man movies seemed good; DC's New52...not so much.
A problem with reboots is, that they sometimes really just want to establish a new Status Quo, but they apparently didn't really think through what to change and what to keep. Look at the New 52, for instance: some characters were completely reinvented, others -like the Bat-Family- just had a few changes. Nothing wrong with that so far. But why on earth give Nightwing a new costume without telling why?(plus I think the blue was more his style. .. black and red looks so dark and gritty, that's not really Grayson's thing.)
Aaaanyway, time to get back to the real problem at hand: Retcons.
What is a retcon?
Sometimes, writers decide that they can't work with the conclusion of old events anymore and decide those events need to be changed. Often this is achieved by time travel, magic or some other super-natural way. Sometimes, things are retold out of another perspective, which reveals things that were unknown up to this point, which causes things to change.
The latter can be an acceptable way to change established facts (I said CAN), the first... not so much.
My favorite (read: most despised) example for a bad retcon would the aaforementioned One More Day.
In One More Day, Marvel Chief-Editor Joe Quesada decided to retcon Peter Parker's marriage to Mary-Jane Watson out of existence.
Now, the normal approach would be a divorce, or -as a more extreme measure- kill one of the characters involved in the marriage.
Quesada however decided to flush the promise, he gave Spidey-fans that 'there would be no magical retcon to fix the marriage' doen the toilet when brought Mephisto into this. Yup, THAT Mephisto.
At the time, Marvel was just dealing it's civil war and Peter decided to give away his secret identity and get registered. Since we all know that superheroes not only have fans, but also one or two enemies, nobody should be surprised to learn, that this was a bad idea.
When Spidey held a speech about this whole registration-act business, an assassin hired by the Kingpin tried to deliver a 50.kal-present right into Pete's skull. Naturally, his spider-sense allowed him to dodge the bullet, but since dodging things doesn't just make them go away, Aunt May took the bullet. Hey, no big deal. We're in a comic-universe and it's a simple bullet wound,right? WRONG! We have lots and lots of doctors, geniuses like Tony Stark or Reed Richards, former surgeon and sorcerer surpreme Dr. Strange, who's magical power is pretty close to bending reality at his will... and nobody can do anything. And no, it wasn't an instant death for aunt May. She was brought in a hospital,where she even told Pete to let her go, since she had a good life. Naturally, Peter Parker ignored that whish and decided to go and find a cure, so he doesn't have to face the consequences of his actions. Good thing that Spider-Man was never about responsibility. ..oh, wait.
Anyway, Mephisto pops up and offers to save her life, of course for a price. Since souls get boring, he wanted something different: Pete's marriage.
He wanted to retro-actively undo the wedding while leaving both Parker and Watson with the feeling that there is something missing in their lives.
Again, since spider-man was never connected to responsibility, Peter Parker agrees.
So much for 'no magical retcon.'
Eventually, the writers realised how stupid that was and it was retconned in One Moment In Time in a way that was even more stupid. (Please, don't ask)
Long story short: I hate retcons, no matter if they were done good or bad. When something was established, deal with it. If you can't, find a way to change things WITHOUT pissing on the past. Yes, I'm also looking at you, Day Of The Doctor. I mostly liked you, but bringing back the Timelords was bull-crap. Yes, it was necessary, due to the regeneration-limit, but I'm pretty sure there would have been other ways around.
No matter who you are, no matter what you do: if it haplened, don't change it. Continuity is there for a reason.
Kirby out (oh by the by, I changed my alias -it's shorter... and easier to make people call me 'Kirby' than 'RestlessEntity' :3)