Twenty-three issues and going on three years ago, the satanically-numbered Batman #666 presented what seemed to be a rare single-issue story in Grant Morrison's then-nascent take on the Caped Crusader. Given the numerological significance of the issue, it was a bit of a surprise that he chose not to feature Bruce Wayne at all, except in flashbacks and indirect references. It was also a surprise that that story in the far-off future actually offered clues to the mystery set in the present. The issue was a key part of the nonlinear narrative that introduced the idea of Lane in issue #665, showed his death in #666, then showed his main encounter with Bruce Wayne in issues #672-674 before he returned briefly in the final pages of Batman, R.I.P. in issue #681. The fact that issue #666 would be part of Morrison's run made it easy to anticipate that there would be a devil-themed story, as there was in Kurt Busiek's run on Superman. It was not as obvious that the Devil would be the main villain of his run, with an influence felt all the way from Morrison's very first issue of Batman through his very (so far) last.
Morrison promised that the story, though set in a "possible future" would "fit in" with his Black Glove mystery and have "some pretty major clues". Indeed it did. Now, Morrison promises that the issue will "form the basis for the final three-issue arc of year one of Batman and Robin." The third arc seems to focus on Dick Grayson's mistake in putting Bruce's skeleton into a Lazarus Pit and raising a monster -- the premise of W. W. Jacob's short story The Monkey's Paw (you may have seen it parodied on The Simpsons). The fourth arc has been the subject of multiple interview comments that align around this idea, most specifically "if people want to check back to Batman #666 and read about Damian selling his soul to the devil, you might get an idea of how some upcoming events might play out." That's a carefully-qualified statement which offers the possibility-expanding freedom that just about anything could happen so long as it ties into #666 -- as Morrison said in yet another interview -- "considerably." Yet another tip-off, not so suprising given the rest of the information, is "Doctor Hurt/Thomas Wayne/The Devil from Batman, R.I.P. will be making a comeback [in Batman and Robin] to finish what he started." The inclusion of "Thomas Wayne" in that descriptor is particularly pregnant with possibility given the pithy comment from the arc's artist, Andy Clarke, that "Bruce Wayne's family tree is the focus of the arc." While Damian alone is enough to fulfill that description, it implies that Thomas Wayne if not some earlier ancestor will likely factor in.
Given the relevance of #666, it's useful to list out what we know from that issue regarding Damian selling his soul to the Devil. That happened considerably before the events of #666, which according to its solicit (but nothing in the issue itself) was set 15 years in the future. Given the quoted ages and times we have, that would mean that Damian, now ten, should make that bargain four years from now at age fourteen, eleven years before the encounter between Damian and Lane in #666. We have several interlocking, but ambiguous, pieces of information that may pertain to the events of the bargain. I have re-ordered them here in likely sequence of their logical relationship:
1) The Batman in the middle of the display case has a large symbol on his chest.
2) Large-symbol Batman lies bloody at a crossroads beneath a grief-stricken Damian.
3) The bargain Damian makes is at a crossroads on the night Batman died
4) Damian has met the Devil
5) Damian bargained with the Devil when he was 14; Gotham's survival in return for his soul
6) Damian is driven by guilt
We also know
7) Damian was responsible for the death of Barbara Gordon's "good friend"
8) Gotham has been left by this time without Bruce or Dick to protect it
9) Something happened to Bruce to pave the way for a Batman like Damian
In principle, even the items that seem to be related could be unrelated; we have no promise that any given pair of these items must refer to the same event. (8) indicates that we have the absences of two Batmen to explain. The simplest explanation is that (1-6) refer to Bruce's death in some event that leads to Damian selling his soul to the Devil. However, we have no promise that what we see in Batman and Robin will adhere to all of those details. For example, suppose that instead of Damian selling his soul on the night of Bruce's death when Damian is 14, the key event is Dick's death when Damian is 10. Meanwhile, (9) could refer to Bruce's death but also to any other relevant event in the past, including RIP and/or the Omega Effect.
Meanwhile, we have other pieces of information about the two stories, some of which promises to interlock. #666 tells us that Damian was "engineered to kill and replace" Bruce. And the solicit for #10 tells us that Talia tries to manipulate Damian "into taking action against Batman." Those two facts point to the same prospect, that Talia will want Damian to strike down Dick Grayson now and begin a less-humane role of her design. Even if he begins to act against Dick and then reconsiders, could his momentary combat with Dick open the door for a tragic incident, perhaps in combination with some other attack? We know that El Penitente has "scores to settle" in Gotham. His revenge on Bruce Wayne could include the death of Dick Grayson or taking Damian's soul. The cover for #10 has another interesting parallel with #666: It shows Batman inspecting bloody footprints; #666 opens with Damian following bloody footprints. Covers do not always depict action inside the issue, but the similarity is striking.
The cast of characters from #666 also factors into the whole Batman and Robin run. Lane, working for the Devil, kills five "bosses", which includes two of the Circus of the Strange villains we saw earlier. Their plan seemed highly reminiscent of El Penitente's plan, but that doesn't mean that they are working for him. It is possible that the Domino Killer represents another big bad in this story, one who is at odds with El Penitente. Then, just as Pyg and Phosphorus Rex are targets for Lane in the future, it could be that Pyg, though he concocted the contagious addiction that El Penitente seems to want, represents another side. And if Pyg's following orders, it is likely to be from the Domino Killer, especially given Pyg's comment about dominoes in #3. We also know that Flamingo works for El Penitente and is one of Lane's recruits in #666. Finally, a coincidence that is not necessarily a tangible connection: One of Lane's henchmen in #666 is referred to as Nikolai -- that's the name of Sasha's father (Niko, the abbreviation of Nikolai) who was driving the car for Toad. Niko is dead long before the events of #666, but perhaps a Russian connection is an enduring part of this plot.
Whether there's one "bloc" of villains in this story or more, it's clear that devilish forces are returning very soon, perhaps constituting the "fearsome and familiar" who menaces Alfred and Damian by Batman and Robin #9 (which is exactly what the preview panel of Doctor Hurt with the keys of Wayne Manor seems to be). If the details of #666 are held to closely, then Damian's deal with the Devil is about four years away. But if they are treated loosely, then perhaps the bargain will come soon with the death of Dick Grayson, even though #666 is more likely referring to the death of Bruce Wayne. If the life of one of DC's oldest superheroes is about to expire, then very big events are in motion.
If the loss of Dick's life or Damian's soul is how Doctor Hurt settles his score with Bruce Wayne, the man who beat him, he's still going to have to give up something significant -- the powers that Damian displays in #666 trump those of the Devil's own messiah. Any bargain would have to be carefully constructed to ensure that the Devil is bound to give great power to a man who, cursing him several times in #666, considers him an enemy.