Origin
Bernie is a taxidermy beaver who Harley Quinn finds in her storage locker. After Joker blows up the locker, Harley takes Bernie with her to Coney Island. Where he becomes her new best friend, that Harley can only hear.
Major Story Arc
Gang of Harleys
For more information see: Harley Quinn and Her Gang of Harleys
When Harley is kidnapped by Harley Sinn, Bernie is oddly missing.
Future End
For more information see: Futures End
Five years later, Harley takes Bernie with her on vacation, and he is there when the plane she’s on blows up. Bernie is then eating by a shark, and all Harley finds of Bernie is his skull. She carries the skull around while on an island full of natives who believe Harley to be a goddess, but when Harley plans on marrying the Joker, Bernie protests. This causes Harley to throw his skull into a pit of alligators. This seems like the end of Bernie, but the beaver makes a return as Harley plans on leaving the island, when Harley stumbles over the corpse of a alligator.