It all had to start with that barbecue.
By the time Red Hood and Red Robin got there, Bruce and Jack had already finished eating. They had not managed to mooch a meal at all.
But Batman and the Joker eating barbecue together was still a bit too shocking. Later, Red Robin discussed it with Red Hood, and they decided they should investigate the matter together.
Asking Batman directly was obviously out of the question, but asking the Joker would not have been much different. Red Robin proposed a pretty good investigative method: go find Gordon.
They believed that, in any universe, Sheriff Gordon was a trustworthy good man. Although he had also been at that barbecue, there had to be some hidden reason behind it. The two thought that was the best place to start.
Barbara happened to still be living with Gordon at the time. They contacted Barbara and went to Gordon's office to ask what exactly was going on between Batman and the Joker.
The mention of it made Gordon furious, because it reminded him of his once-in-a-millennium Royal Flush. It might have been the best hand he would ever see in his life—there had never been one before, and there never would be another—but the Joker had ruined it just like that.
While explaining the whole process to Red Robin and Red Hood, the relatively younger Gordon could not help complaining to the two Robins a few times.
Red Hood was fine, but Red Robin's detective instincts flared up again. He instinctively asked Gordon for the details. Gordon had been wondering about it himself, so the group sat down and studied it together.
At the time, Jack's cards could have made four of a kind, while Gordon was one card short of a Royal Flush. The