Introspective character piece. An alternate interpretation of the Joker, partially inspired by his appearance in Mask of the Phantasm.
The fact of it is that the Joker remembers more of his past than he usually lets on, and when dredging up old favors he sometimes makes use of it. It is easier to be an unpredictable mystery if your past is shrouded, unknown to even yourself, and it puts people off guard; furthermore, he appreciates the drama.
If you ask anyone on the street what they had for breakfast that morning a week ago, chances are they wouldn't remember. You could enter into any number of 'normal' people's heads and find great swathes of empty spaces in their pasts, held together with those instances memorable enough, with enough emotional impact, to last; a word or a gesture might be preserved in stunning color for years while whole days drift away in the waters of Lethe. From what the Joker has observed, it is not the function of how memories are preserved that differs in his mind from those of other people, merely the frequency of those things which strike the heart with enough force to lodge itself there. True, he has passions; joy and anger in wild extremes; a sadness burdened with tragedy that would rival those of the Classics, even the occasional bouts of apathy stand out by their very rareness, but perhaps because of that constant overload of feeling the stand-out moments are few and far between.
Then there is of course, the ordinary person's preoccupation with the self as an individual; how someone will take those small moments of memory, link it with causality, shore it up with society, and create a comfortable illusion of the continuance of memory and of an individual that simply does not exist. The Joker has noticed this, even recognizes its limited effect on his own being at times, how the regard of others will confine you with their expectations, hold you to an arbitrary space of mannerisms and thought within which is 'you', without which is not. It doesn't rankle him, because he realizes the use of it. As much as he may be an agent of chaos, he knows that without order there would be nothing to shake up, and he feels no obligations to the selfs others create for him. He's changed his self many times, perhaps more dramatically than most. Always it happens at a moment of inspiration, one of those few times that stick in the memory because they had touched something within, and then he is created new, as easily as changing clothes, and everything before that, well, it simply has no power to reach him anymore. That does not mean he has forgotten his past, but it might as well have belonged to a different person for all it means to him now.
That's not to say there aren't certain patterns, or similarities, that seem to come up in his various lives; he remembers times when he had not been "the Boss" and he knows his other selves were discontent in those situations. The Joker enjoys power; always has, probably always will, though he holds no presumptions of knowing the future; it certainly may be that someone he later decides to be will decide to have none of it, though as such patterns of similarity between selves are rare and very evident when they appear, he tends to think it unlikely. True, there have been times—occasional times—in his past when he has abandoned power for something other, but it has never brought him contentment. The Joker holds something like contempt for the versions of himself that would hold to such an endeavor, because to the Joker, fun is the ultimate end of any action. That is not a pattern though, he knows that most people—and many of his past selves—have had other ultimate preoccupations. It is all one and the same really; with the self being so ambiguous, though most of society seem to try their hardest to deny it, one does need a purpose to life.
The Joker prides himself on knowing exactly what his purpose is. He has known it since he became the Joker, when he looked at Batman and his self fell into place beside the Dark Knight, the perfect and everlasting antagonist, and if ever the Joker looks ahead to some future self—a rare thing, for to the Joker, time is very nearly meaningless, the present the only thing that holds any appeal and the only thing immediately gratifying—he knows it will be only after the Batman has died, or become boring—and yet there is something in him that seems to almost desperately wish to believe that the Batman will never become boring. He's never let him down yet, but a pattern is only a pattern, giving probable weight, but not inevitability. On other days the Joker thinks about defeating Batman once and for all, and on those days he thinks of his death—not the death of the Joker to give way to another self, but a death to him, to all he has been and could be, with his body broken and the Batman the one who did it, because it would be the most wonderful triumph, a bigger triumph than the whole history of himself has ever had, and he wonders what it will feel like.
Batman is the reason for Joker's existence, and the Joker loves him for it, for multiple reasons. For one thing, he enjoys being himself, and he is grateful for the Batman for giving him the memory which brought him to that experience. For another, he can respect Batman, a rare thing, and sometimes he is even sure that Batman recognizes his importance and carries the weight of the Joker's existence on his shoulders. It's kind of nice. No one has ever done that for him before. Other people have loved him, and he has loved others, in different ways, but the Joker cares about the theatre of it and Batman is the only one who can play with him on an equal footing, with as much drama as the Joker, so that there are no hierarchies but only dualities.
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