WARNING: The following contains spoilers for Justice league Dark #23, by James Tynion IV, Ram V and Kyle Hotz, available now from DC.
An outsider and prototypical anti-hero to the core, it's difficult to discern John Constantine's motives at the best of times. In Ram V and James Tynion IV's Justice League Dark #20-23, "The Parliament of Life," Constantine's tendency to hold his cards close to his chest remains firm, leaving the JLD in the dark until the very end, when he pulls the rug out from everyone -- and ultimately, saves the day.
More specifically, he saves Swamp Thing. Constantine restores Alec Holland after the Floronic Man rendered him down to sludge in Justice League Dark #16. Unfortunately, it's seemingly at the expense of everyone else -- until it isn't.
At the beginning of Justice League Dark #23, the various elemental parliaments are out of balance because of Swamp Thing's demise. Now that he's gone, trees are no longer growing in the Green; to make matters worse, the Floronic Man is imprisoned in the Hall of Justice. A war breaks out as the parliaments fight each other for dominance. To restore the world to what it was, they have to be reconvened through the same ritual that created them.
Constantine makes a deal the Floronic Man and frees Abigail Arcane from the heart of rot, then makes a deal with her as well. Meanwhile, Nassour heads to the Serengeti to convince the avatars of Stone, Wind, Vapors and Flame to reconvene the parliaments.
Once the parliaments are reconvened, Nassour begins the ritual. The Guardians have to give up their power over their respective parliaments. They start with the Floronic Man, with Constantine reminding him about their deal in a whisper.
Next up is Animal Man, then Abigail. Instead of giving up her guardianship, she attacks the parliament of flowers, causing them to decay. The rest of the JLD try to restrain Abigail, while the parliaments erupt in anger at the betrayal. Constantine rummages in the rot and absconds with a seed.
He flees to the Green, where he meets up with Aton Arcane, who senses a change in the parliaments. John is ever-illusive, but eventually reveals the secret goal behind all his back dealings: Swamp Thing has returned. When he plants the seed in the Green, he restores its former guardian because trees are growing once more. This also rebalances the parliaments.
Although Constantine couldn't have known for certain that his shady plan would work, he managed to restore Swamp Thing and fix the situation -- even though he kept secrets and betrayed his team in the process.