The Joker is one of Batman's arch-enemies. In Lego Batman: The Video Game, he attacks with joy buzzers and twin pistols (also uses bladed playing cards in the Nintendo DS version). He was once a small-time thief who had planned out a heist in the Gotham Chemical Plant, but when Batman came to apprehend him and his cronies, he then tried to escape the Dark Knight on his own. Batman would eventually come for him and the he fell into a vat of chemicals, which turned his hair green, bleached his skin white, and stained his lips red and stretched them out into an everlasting smile; it gave him the appearance of a crazed clown. Driven insane by this reflection, the unknown crook then named himself the Joker and would become one of Gotham's most sadistic and twisted crime bosses. He may be insane but he is also a genius, having knowledge of chemistry, physics, and engineering and he invents gag-based gadgetry whilst concocting criminal schemes. The Joker also cheats death frequently, having been thought killed several times only to come back and wreak havoc once more. He has many minions serving under him, most notably his self-proclaimed lover Harley Quinn who herself was once his psychiatrist. The Joker is a mass murderer and has been known to kill many people, even his own henchmen.