Plastic Man was an ally of Batman.
Patrick "The Eel" O'Brian was a member of Kite Mans gang. When Kite man and his men tried to rob a chemical factory, Batman showed and stopped them. During the fight Plastic Man was knocked into a vat of chemicals. In court Plastic Man helped testify against Kite Man. Batman then promised to take care of Plastic Man's rehabilitation.
Terror on Dinosaur IslandEdit
After defeating Gentleman Ghost with help from Fire, Batman and Plastic Man tracked down Gorilla Grodd to Dinosaur Island. Batman was captured and Plastic Man has a flashback to when Batman pulled him out of the chemical vat during the Kite Man fight. Meanwhile, Grodd talks to Batman and gives him the offer of joining "my noble cause", to which Batman replies "My only cause is to send you back to the zoo." Grodd then blasts Batman with his "E-Ray", no doubt standing for 'Evolution Ray'. Batman is turned into a short, fat gorilla, with his costume still on. Plastic Man arrives and they eventually took Grodd down, turning him into a naked man, by which he is disgusted, and human Batman takes him down once more with one punch.
Plastic Man apparently was rehabilitated as he took down Babyface with Elongated Man. Batman may have handed over the responsibility or he could just have charged with Elongated Man with watching him while he was away.
Game Over for OwlmanEdit
When Owlman was committing crimes dressed as Batman, Plastic man helped a group of heroes attempt to catch him. Plastic man failed miserably managing to lose batman, get tied up or frozen.
Plastic Man's criminal nature never fully left him. He still has a love for money and would even try to sneak stuff in behind his teammates' back. He, however, proves witty and durable in some situations, especially at the last moment.