There are certain aspects of the Batman mythos that fans hold very dear and believe that they should always be constant. Bruce's parents are really dead and they stay dead. Batman doesn't kill.
However, one such aspect is the Joker's origin, or the lack thereof. The only aspect that is generally agreed upon is that Joker was once the Red Hood, and during a confrontation with Batman, he fell into a vat of acid in ACE Chemicals and ended up turning into the Joker. Whenever a writer even attempts to give a hint as to who the Joker is, it usually frowned upon by fans, as it is believed that Joker's mystic is part of the character's appeal. Whether it's "Jerome", "Jack Napier", "Red Hood One" or "Joe" the mobster or the nameless struggling comedian and widower, many fans believe that Joker should not have a definite origin because it takes away from the character, and that is attributed to one infamous line from the acclaimed The Killing Joke story (which ironically also hinted at an origin) "If I'm going to have an origin story, I'd prefer it be multiple choice!". Adding fuel to that line thinking was Nolan's Dark Knight where Joker tells two different stories of how he "got his scars" and even attempted to tell one more.
My question is, if for some odd reason someone finally decided to give Joker a definite origin, will it negatively impact the character? And unless they repeatedly hit us over the head with it, does it really matter? Some believe that Joker's lack of origin makes him that much scarier but when I think of the Joker, his threat as a villain appears to me because of his grotesquely grinning victims, because of the menacing laugh, because of the fact that he'll kill and maim many innocents just for fun, because of the fact that he pushes Batman to his limit everytime they fight, because of the fact that he is so obsessed with Batman he's willing to burn the entire city just to prove the point that they're both crazy. I'm speaking for myself of course, but when I think of the Joker, those are usually the things that show why he is such a menacing villain, not because he has a mysterious origin.
Other arguments I've seen include Joker's origin being the only case Batman, the detective, could never crack, which adds to the complexity of their relationship. While that is appealing, outside of the recent Death Of The Family and Endgame, is rarely addressed in storylines and it's even rare to see Batman even attempting to figure it out.
Another argument is that giving Joker an origin make him a sympathetic character, and Joker is an amoral murderer who should not be given any sympathy and therefore, should not be given an origin. I've seen comparisons with Marvel's Wolverine who, after many years of having a mysterious past, was finally given an origin story, and many fans claim that by doing that, Logan lost his appeal. However, Logan is considered a hero and so him becoming more sympathetic is more appropriate than Joker. In Joker's case, if his origin actually didn't make him more sympathetic, will that still affect the character negatively?
So, in conclusion, Joker's mysterious past, does it play apart of the character's appeal? When you think of the Joker, is his lack of origin one of the first things you think about? Will Joker become less intriguing if he was given one? Sound off in the comments.