The following contains spoilers for Task Force Z #12, on sale now from DC Comics.
Gotham City treats everyone horribly at some stage, but Hank and Claire Clover got some of the worst the city had to offer. All they wanted to do was emulate Batman, with Superman-esque powers and matching costumes too, as Gotham and Gotham Girl. Unfortunately, they fell victim to the machinations of some of the Dark Knight's biggest and most powerful villains. Shortly after their first appearance, Gotham was sent into a rage by Psycho-Pirate. A fight with the Justice League caused him to use his powers too much, killing him. That sent Gotham Girl into a downward spiral too, which she's still recovering from.
The two siblings were reunited in Red Hood's zombie romp, where Claire teamed up with zombie Hank in an unfortunate alliance with twisted villain Mr. Bloom. Everything was resolved in Task Force Z #12 (by Matthew Rosenberg, Eddy Barrows, Eber Ferreira, Adriano Lucas, and Rob Leigh) and Claire and Hank finally got a happy ending. Knowing their luck though, it was bittersweet and a little twisted.
Gotham Chose His Own Fate
Although Gotham could have been revived fully with the remaining Lazarus Resin, he told his sister he wouldn't take it. Gotham Girl once tried to revive her brother before, and was sad to hear his decision, something Gotham himself understood. Nevertheless, Hank finally had a say in how he lived his life. Resurrecting himself now, using the tools of yet another villain who manipulated him, didn't feel like living his life his way. After being manipulated by Psycho-Pirate, Bane, and now Bloom, Gotham decided that this was the only choice he had that was his and his alone. Hank asked Claire if she wanted to do all the things they never got to do for the rest of his life, however long that is.
Then, they flew off to live their bittersweet happy ending, even if it only lasts a few days. The thing is, there are actually a few major holes in Hank's plan. The biggest of which is the fact he is very much still a zombie. Task Force Z has shown these zombies at a number of stages, which is entirely dependent on how much Lazarus Resin is in their systems. If an individual got enough, they could be resurrected permanently. However, Two-Face and his team made sure they only got enough to be on the cusp of life.
They needed a constant supply to be reanimated in any form but were fed a small enough dose each time that they were dependent on the Resin for this false form of life. Gotham clearly had a large dose, as he was capable of talking coherently. However, after a few days without another dose of Resin, he won't be able to talk at all. With a little more time, he'll be totally feral and craving human flesh. It's likely that, at that point, he'll try and eat his sister or another innocent bystander. After that, he'll be unable to do much at all and slowly return to being completely dead once again.
Hidden Horrors Are Still On Gotham's Horizon
As seemingly sweet as this ending is then, it's actually a lot more horrific than it seems. For Claire, who has been tortured by the death of her brother and both of his failed resurrections, it's going to be a terrible experience. She recently featured in her own backup story in Detective Comics, focusing on her mental health. Even though she's been released from Arkham Tower, she's far from recovered. Seeing her brother slowly devolve into a mindless, feral zombie will be painful. The fact that she may even have to kill him before he hurts anyone else could even cause her to have another breakdown.
Although Gotham is going out on his own terms, the way he's doing it is kind of selfish. He knows as much, as he asked Claire if she wanted to go with him and said he would have understood if she said no. Nevertheless, she agreed to this farewell tour. We're unlikely to see what Gotham's final days look like, but they're sure to be far from perfect. The pain they cause to Gotham Girl could leave a lasting impression that ensures this happy ending is far from happy at all.