Trophy and Achievement leaks are a wonderfully teasing ways of subtly announcing DLC packs. PS3Trophies.com uncovered 10 new Trophies for an unannounced Batman: Arkham City DLC pack, and we're left to ponder their context and significance. There's mention of Harley Quinn, and of Robin fighting in Harley Quinn's Revenge, but otherwise the rest is a riddle, err, joke.
The first four Trophies allude to a quest series for Harley, requiring her to perform certain ambiguous tasks, but containing no significant plot points. One in specific is titled "The Last Laugh" with the subtext "The joke's on who?" which should persuade almost all players of the Arkham City campaign that this could be a must-buy DLC pack.
Gameplay actions fill in the rest of the Trophies, requiring you to Zip Kick, Shield Bash, Snap Flash and destroy Harley Balloons -- probably Riddler token-esque items scattered around the world. All in all, it sounds comparable to the Catwoman DLC in size, but could potentially take place after the game's end story-wise. Does this mean you can expect a true ending via this DLC? Or perhaps I'm wrong and this is just a supplementary side-story. Hopefully we'll here more from Rocksteady about this DLC soon.