Expansion Pack Past/Playing With

Basic Trope: A character's backstory is one big Continuity Snarl.
 * Straight: The one thing anyone can agree on regarding Mysterio's past is that it's mysterious. The details vary Depending on the Writer.
 * Exaggerated: The only way all this stuff could have happened to one person is if he's a Time Lord.
 * Downplayed: There are minor inconsistencies between different version of his past, but they can be overlooked either by invoking the MST3K Mantra or assuming the narrator has an imperfect memory.
 * Justified:
 * Mysterio is Unstuck in Time or has otherwise fumbled the Timey-Wimey Ball in such a way as he has multiple contradictory backstories that can't be reconciled.
 * He gives different people a different version of events either to amuse himself, or because of a Split Personality.
 * Inverted: Mysterio is introduced with a Multiple Choice Past. Over time, this detail is surreptitiously dropped for seeming silly, he's revealed to be a fantasist, and his real past is exposited in great detail.
 * Subverted: Mysterio has a consistent past.
 * Double Subverted: Mysterio says has a consistent past, but he's wrong... or lying.
 * Parodied: Mysterio contradicts his stated backstory twice within the same conversation. His friends exchange puzzled looks.
 * Zig Zagged: Mysterio's inconsistent backstory is an acknowledged problem with the series, but different authors have different ways of rectifying it - retcons, Unreliable Narrator, Multiple Personalities, awareness that he's fictional and can tell who's writing him at any given moment, you name it. Naturally, this just leads to even more inconsistency...
 * Averted: There's a very detailed Universe Bible which tells you all you could ever want to know about Mysterio's past.
 * Enforced: There's a Running Gag that each new writer introduces a new detail to Mysterio's past that's as inconsistent as possible with previous writers' contributions.
 * Lampshaded: "Wait, M, did this happen before or after you went to ninja-school in the Himalayas?" "...Shhh! I don't like to talk about that!"
 * Invoked: Mysterio tells different people different versions of his history to make himself even more enigmatic.
 * Exploited: Mysterio becomes aware of his inconsistently-detailed past, and in a moment of Breaking the Fourth Wall teases the readers that he's not going to tell them which one is right because he likes the mystery of it.
 * Defied: Past versions of Mysterio's history are explicitly Retconned out of existence.
 * Discussed: "So, what did Mysterio tell you about his past this time?"
 * Conversed: The characters lean heavily on the fourth wall when they watch a Show Within a Show and self-deprecatingly mock its use of the same trope that plagues their own series.
 * Plotted A Good Waste: The inconsistencies in the Mysterio's backstory are all revealed to be his Multiple Personalities telling their own version, Rashomon Style. Going back over past issues with this new knowledge, you can see which personality was in charge at which points in the story, thus explaining away hordes of other continuity "goofs" at one fell swoop. Incredibly-long-in-the-making twist, or brilliantly executed Ass Pull?