So. The Joker.
He's one of the most iconic bad guys in comic-dom, and - especially when played by Heath Ledger - one of the most memorable screen villains in recent years.
The Dark Knight's Joker, though - as played by Ledger - might well be hiding a huge secret behind that grin.
That's right, it's fan theory time - and we're going old school. Specifically, to a theory that's been doing the rounds for a few years now - but that, with Jared Leto's casting as The Joker in Suicide Squad deserves another look, just in case any of you missed it.
The theory? That The Joker is a war-veteran.
The Joker is a Gifted Tactician
All of those plans The Joker has? The grand, epic, incredibly complicated schemes, which he orchestrates in exact and incredibly specific detail? Where else would he have learned the level of precision needed to pull them off than in (a presumably fairly senior role within) the military?
The Joker is an Arms Expert
He may well know he's not quite a match for Batman when it comes to hand-to-hand combat, but The Joker is still a talented marksman, and an obvious expert in explosives. And, when it comes down to it, pretty darned handy in a fist fight. The fighting and gun-toting he might have learned on the streets - but the explosives? That suggests training...
The Joker Understands 'The System'
Specifically, he's able to easily blend into that police funeral ceremony - as well as to understand the likely responses of Gotham's entire police and military response to the crisis. That suggests an intimate - and inside - knowledge of the goings on within them.
The Joker Has a Motive
Or at least, it sure sounds that way. Remember what he says to Harvey Dent, after he becomes Two-Face?
"Nobody panics when things go "according to plan." Even if the plan is horrifying! If, tomorrow, I tell the press that, like, a gang banger will get shot, or a truckload of soldiers will be blown up, nobody panics, because it's all "part of the plan". But when I say that one little old mayor will die, well then everyone loses their minds!"
That sounds an awful lot like a motivation for a military man - traumatized by war, and by what he sees as 'the plan' and its victims - to become The Joker.
What Does That Mean?
Well, basically, that The Joker was once in the military - and that at some point, something happened that pushed him into the arms of chaotic madness.
Whether that something happened while he was serving in the regular army, while he was part of a special ops team, or even in another section of the military entirely is a whole other question, though...