From the article for cr0w:<code> I'm prepared for my theory to be shredded, but here goes:<br>The Joker is ex-military.<br>My theory is based on what I interpreted from the following dialogue and actions:<br><br> His hand-to-hand combat skills. He grabs a dudes arm and puts a pencil through his face. Something a trained fighter might do, not something a typical street thug might attempt. The Joker seems trained in fighting.<br><br> He knows how to use grenades. He enters Gambols meeting with a jacket full of grenades. Also, he uses a gas grenade on the bank manager.<br><br> He knows how to use a Rocket Launcher. That's an anti-aircraft weapon he's firing at Dents escort. Not your typical criminal weapon.<br><br> He can drive an 18-wheeler. (Ok this one's a stretch, but I imagine him driving a truck in Iraq)<br><br> His scars. He lies about them. Battle left him disfigured.<br><br> When he talks to Harvey at the Hospital, he talks of a truck full of soldiers being killed and no one batting an eye. But one little Mayor being killed and everyone losing their minds. Seems bitter about something that happened. Possibly losing his brothers, or maybe that's how he got his scars.<br><br> He loathes the Government. He tries to assassinate the Mayor, and succeeds in murdering high ranking Gotham Players. I think (hey it's my theory!) he was dishonorably discharged, and he came back with a vengeance.<br><br> His smacking of the lips, that is behavior of a drug abuser. Soldiers sometimes turn to drugs when our government turns their back on them.<br></code>