Hades is the God of Pluto. Hades is sometimes mistaken as Pluto. Pluto is a Roman God. Hades is one out of the six major Olympians. Hades and his brothers divided into thirds, each of his brothers took a 1/3 each. They drew straws to see who chose first. Zeus chose the sky, Poseidon chose the Ocean leaving Hades with the underworld.  Once a mortal is in the underworld they can not  leave without Hades permission. Only Herakles and Odysseus may  leave the underworld.
     Persephone once had been abducted by Hades.  (In the picture above Persephone is on the left and Hades is on the right.) Hades captured Persephone by dragging her to the underworld and trying to keep her there. Zeus and Hades kept her there for seven years. Demeter forced Zeus to give her back Peresphone. Zeus then sent Hermes to persuade Hades to let him go.