As much as I love The Watchmen (see my alts name in my sig), it's already a long shot to get one DLC so I highly doubt we'd get two. So if we DID get just a single Watchmen episode, it'd probably be the one that takes place in the DC Universe, Doomsday Clock. I'm pretty sure DC Comics only acquired the rights to the characters and not the original Alan Moore graphic novel content so it would have to be Doomsday Clock. Since it's a pretty massive and episodic narrative, it'd probably pick up with Batman contacting us and telling us that a strange man calling himself Rorschach somehow broke in to the Batcave to seek his help to find someone or something called Manhattan but it made no sense. Being clearly insane, he was able to trick him and lock him in Arkham. What's funny is there is another thread discussing how DCUO had to move away from separate hero and villain story lines. Doomsday Clock would actually be perfect for this format as there's a whole parallel villain story line during the first half of Doomsday Clock with Marionette and Mime palling around with the Joker and later Adrian Veidt and Lex get together finding kinship in their both being considered the smartest person on the respective earths.