But was Violet always a character in a "different universe"? Didn't they say the Young Animal line was still suppose to be (somewhat) connected to the main DC universe? Doom Patrol used characters from the main DC universe, and haven't Batwoman and Batman (among others) appeared in Mother Panic?
And while it's not an example of " the last time at DC a character from a completely different universe just showed up in the main one with no explanation", what do you call Harleen Quinzel and Renee Montoya?