WARNING: The following contains spoilers for the story "This Man, This City" from the Dark Nights Death Metal: Legends of the Dark Knights #1 by Frank Tieri, Francessco Francavilla, and Andworld Design, on sale now
The Dark Multiverse is full of twisted and corrupted versions of Bruce Wayne, many of whom made terrible sacrifices for their own idealized version of their mission for Gotham. One of them even proved willing to sacrifice his only remaining family for a chance at saving his Gotham, and doomed himself to an even worse fate in the long run.
In Dark Nights Death Metal: Legends of the Dark Knights #1, one version of Batman from the Dark Multiverse is revealed to have fused himself with his crumbling Gotham City by making a literal deal with the devil and killing his son, Damian. And considering the fate he's been teased to have suffered in the Metalverse, it was all for nothing.
THIS MAN, THIS CITY
On the surface, this version of Batman appears similar to the potential future of the Batman of Bethlehem, a world where Damian Wayne took over as Batman in an increasingly grim future. That was a reality where Damian's deal with the devil led to the destruction of most of Gotham. However, the world introduced in "This Man, This City" may actually be worse off: Arkham Asylum has been destroyed and legions of criminals -- seemingly led by the Joker -- have escaped into the city. Many of their former allies, including Dick Grayson, Jason Todd and Tim Drake have all been killed. Police Commissioner Barbara Gordon has been assassinated, removing the last steady hand from leading the Gotham City Police Department.
This has allowed legions of gangsters to move through the city, along with swarms of Killer Crocs and Clayfaces. Watching from Wayne Manor, Bruce Wayne grimly speaks to Damian, who admits that he's failed as being Batman. Bruce agrees, and reveals he's discovered a spell that could be used to sacrifice a loved one, binding them to a dark god and empowering them, "making them part of Gotham itself." Damian is initially shocked but is seemingly at peace when he realizes Bruce instead means to sacrifice him to empower himself. After ritually killing Damian with a knife to the chest, Bruce uses his blood to paint a dark sigil on the ground, which promptly bursts into flames.
Walking into it, Bruce Wayne's body disappears and his essence takes control over the city itself. Every street, every building, and every aspect of Gotham becomes an extension of this murderous Bruce Wayne, so that he may protect it forever. But that eternity may have been far shorter than he intended. In the interactive map of the DC Metalverse, Castle Bat is described as being "once a living city." The dark version of Gotham now exists as the main base of operations for the Batman Who Laughs and his council of lieutenants, which means one of two things has happened to this version of Gotham.
This suggests that this version of Bruce Wayne was broken by the Batman Who Laughs and his allies, and is no longer the strictly alive city that Bruce bargained to become. It could have been a demented version of Danny the Street from the Doom Patrol, but it could be less of a threat if it's lifeless. The other possibility is even worse, that this Bruce Wayne has fully aligned with the twisted Batman of the Dark Multiverse. No matter what, this fate for the living Gotham City means the sacrifice of Damian was for nothing in the long run. His demise only allowed Bruce to turn Gotham into an even more potent and fearsome threat.