"I want them dead! I won't let them hurt my babies again!" Ivy yells through a loudspeaker as Hulk and Batman walk through the greenhouse.
"I can't believe you guys left poor little Ivy crying in her garden. She looked so sad." Joker says, joining the conversation. Suddenly, large vines erupt through the floor and walls, keeping the two heroes from leaving through the main entrance. "I gave her a little Titan..." Joker adds. "Gotta say, the results are a little different. Shall I give her another? I think she wants it." Joker says, followed by a scream from Ivy as the ground rumbles. "They don't call you Ivy for nothing, do they, dear? I was hoping for a 40 foot killer plant, but you do t always get what you want, do you?" Joker asks Ivy through the loudspeaker as Hulk and Batman struggle to get past the vines, though Hulk is able to lift the large, pulsating vines long enough for the two to exit the greenhouse.
-Outside-
Batman and Hulk's eyes widen as they see large plants sprouting all over; these plants were as big as houses.
"Titan must be having a different effect on Ivy. Her plants are growing; they'll soon be out of control." Batman says as he looks at the overgrowing flora in horror as one of the maniacal inmates approaches a man sized plant pod, which fires a spore that instantly knocks him down. "Looks like the plants are mutating further." He adds.
"Ouch. This looks bad..." Hulk says in response to the small pod's surprising lethalness.
"That pod appears to contain similar spores to the ones Ivy used to attack Gotham last year. They're deadly." Batman surmises.
-Later-
Arkham Mansion
After making short work of the plant pods, Hulk and Batman enter the mansion the same way as before, noticing lethal plant spores flooding the entire area. The two heroes get around that issue by using some nearby catwalks that keep them above most of the spores.
"Batman! Hulk!" A voice called out below, which turned out to be fellow officer Aaron Cash, who, along with another guard, were down below, but appeared to be unharmed by all the spores. The two heroes jump down and look at Cash. "I figured you two would be here by now. What's the deal with the plants?"
"It's complicated." Batman says, receiving a raised eyebrow from Hulk.
"Let me guess. Poison Ivy. She teamed up with Joker." Cash says, knowing exactly what the issue was.
"So much for being complicated." Hulk sarcastically says.
"All that matters is that we stop the plants taking over the island, but..." Batman begins to say, only to stall.
Cash sighs. "There's always a but, isn't there?"
"Where do you keep Killer Croc? We found a door in the sewers, but it's sealed shut." Batman asks.
"That monster's got his own special cell. It's right below the transfer room back in Intensive Treatment. Elevator goes right down to an old sewer. We just drop meat down there every day or so and try to forget about him. It's locked off; more security than the Joker. You won't get in without the Warden's permission. He has the codes." Cash says.
"Thanks, Cash. Stay here and do not go near the plants. They'll kill you." Batman warns.
-Intensive Treatment-
Hulk and Batman enter. Because the coast is clear, Hulk transforms back into Bruce Banner. As Bruce and Barman walk down a hall, the loudspeaker turns on. "Did anyone watch the game last night?" This greatly confused the two heroes before they started to feel woozy.
"What the...?" Bruce weakly asks as he struggles to stand up straight.
"Scarecrow...his Fear Toxin..." Batman surmises.
-Batman's Hallucination-
Batman starts to see things in reverse. He's the one in cuffs while Joker is driving the Batmobile to Arkham. Once inside Arkham, Batman is strapped to a gurney as he is pulled down a hallway by Victor Zsasz while Joker and Harley follow, the latter of which is holding an assault rifle.
"Can I keep him, sweetie? Please, please, please? I'll feed him and walk him. I promise." Harley says, swaying her hips as she follows the restrained Batman, followed closely by Joker.
"You have to listen to me! It was a mistake! I didn't do it!" Batman maniacally screams.
"He don't look so big and scary now, does he, Mr. J?" Harley asks as the gurney stops.
"Just got to check your prisoner, dear." Scarecrow says, holding a clipboard in his hands.
"Whatever, just be quick! He's not looking too good." Harley says impatiently as Scarecrow analyzes Batman.
"No, he's not. We really should feel sorry for him. He never fully got over his parents' death. It left him quite insane. What is going on inside your head, Wayne? Bah, he's gone. Just a twisted shell of a man." Scarecrow says as he keeps analyzing Batman, who suddenly lunges his head towards the criminals.
"Cut me free!" Batman screams out, making Scarecrow jump back in surprise.
"He's all yours, Joker." Scarecrow says, satisfied with his results.
"Oh, goody! Come on, Mr. J. We're ready." Harley says excitedly.
"I've waited a long time for this, Bats. Let's start the party." Joker says as he pulls out a handgun and points it at Batman's head. "With a bang!" He says before pulling the trigger.
-Bruce's Hallucination-
Bruce Banner wakes up in the streets of a decimated Gotham City. After wandering around for a bit, genuinely confused by his surroundings, he comes across a most disturbing sight: several dead superheroes lying on the ground, including Superman, Flash, Cyborg, Zatanna, and Aquaman. Bruce than sees that Wonder Woman is among the corpses. He quickly runs over to her and cradles her lifeless body.
"No! Diana! No...No, please, no!" He says as he begins to cry. "Don't leave me..." He tearfully pleads, his forehead touching hers as he hears Batman groan.
"Why, Bruce? You were supposed...to be our friend..." The caped crusader groans weakly before dying.
Bruce then realized what happened in his hallucination as he saw his hands change to that of the Hulk. He would be the cause of the fall of the Justice League, if not every other superhero that Hulk comes across, regardless of their abilities. "What is happening to me?!" Bruce screams as he changes into Hulk and roars in sorrow.
-Batman's Hallucination-
Batman punches his way out of a grave marked, "R.I.P. Bruce Wayne." After climbing out of the grave, Batman comes across manic versions of himself, including one feeding off of a dead rat. He jumps across several ledges before coming into contact with the giant Scarecrow once again. Like before, Batman easily outmaneuvers Scarecrow and makes it to a Bat-Signal, only to warp back to reality, where he quickly injects more Fear Toxin into the two weakened heroes.
"I think you two need a little more!" Scarecrow says as he doubles the dosage, making the two heroes warp back into their hallucinations.
Back in Batman's hallucination, the floor collapses beneath Batman, which leads him to fall in a caged up area where Scarecrow looms over him. "Are you enjoying the extra dose, little bat?" He taunts as several skeletons crawl out of the ground and attack Batman. "I won't rush things this time. I'm going to savor every moment of your terror as I slowly destroy you. And then...I'll tear apart Banner's pathetic mind!" He says as he sends more skeletons, including several that resemble the Titan henchmen. Despite all this, Batman prevails, breaking free of his hallucination and grabbing onto Scarecrow.
"How are you two doing this?! You both ingested enough toxins to drive 10 men insane! What are you?!" Scarecrow exclaims as he breaks free and runs away. "Why fight it? You're both as crazy as the rest of us! You need us as much as we need you and that monster. And to prove it, I'll flood the catacombs with enough Fear Gas to break the minds of everyone in Gotham for a hundred years." Scarecrow's ethereal voice hollers out as it slowly fades. Batman walks over to Bruce, who is clutching his head and crying out Diana's name over and over again until Batman slaps him.
"Bruce, it's not real. It was Crane. Whatever you think you saw...it wasn't real. He's getting away; we need to catch him. Now!" He says sternly, to which Bruce nods as he wipes some tears off his face.
-Secure Transit-
As Bruce and Batman enter, they notice an elevator lowering itself before hearing Scarecrow cackling to himself. As the elevator reaches the bottom of the facility, a large metal door closes above it, cutting the heroes off from Scarecrow.
-Croc's Lair-
After maneuvering past the elevator and its many obstacles, Batman and Bruce, who recently transformed, enter the sewer that no doubt was being used by Croc. The two approach a plant identical to the pods from earlier, only to hear Scarecrow call out.
"Too late, heroes! One step closer, and this goes into the water!" He says as he holds up a bag full of Fear Gas. "The cave will fill with your deepest, darkest nightmares, and you will never reach your precious Venom roots."
"I'll kill you for what you put me through!" Hulk says threateningly, though Batman holds him back as Scarecrow dangles the bag over the water.
"Hulk, no! Don't do it, Crane!" Batman says as Scarecrow begins to cackle. Unbeknownst to any of them, Killer Croc surfaces and grabs Scarecrow and lifts him over his head, making him drop the bag harmlessly on the ground. Acting fast, Batman tosses a batarang into Croc's shock collar, activating it. As the electric currents surge through him, he leaps into the water, still holding Scarecrow.
"Croc. Fantastic." Hulk says in response to what just happened.
-Later-
After adjusting to being in Croc's home turf, Hulk and Batman maneuver around before entering a section of the sewer.
"Oracle, we're heading into Croc's lair to collect the plant spores Ivy spoke about. He's in some kind of old sewer network. Send us the schematics. It's like a maze down here."
"There's nothing on record. Bruce, are you sure about this? It sounds like a suicide mission." Oracle asks.
"We don't have a choice. I've tuned the scanners to detect the spores required to make the Anti-Venom. It'll lead us straight to them." Batman says
"What about Croc?" Oracle asks.
"Croc's just an animal, and animals just need traps and the right bait. We'll be fine." Batman says as he sprays a large amount of Explosive Gel onto the ground.
"I hope..." Hulk says softly as they enter Croc's lair, which as lots of wooden platforms floating above the water. Much to the two's surprise, they can hold the combined weight of the two.
"These floating platforms will support us, but will also send sound waves through the water, giving away our position to Croc. We'll need to move as slowly as possible." Batman says to Hulk, who nods.
As the two carefully navigate the labyrinth like sewer, they come across a spore and Batman begins to extract the genetic material, only for Croc to surface. Before Croc can reach Batman, Hulk tackles him into the water. The two titans exchange blow after blow, with Hulk emerging from the water victorious while Croc swims away.
"Blegh! Remind me to shower after this!" Hulk says in disgust at the fact he just swam in sewer water. Sewer water that Croc was swimming in.
"Noted. These spores don't contain enough of the Anti-Venom. We're going to need to find more." Batman says, to which Hulk nods as the two begin to search for more, only to be attacked by Croc again, who bursts out of the water and stands in front of Hulk. He growls before swinging his right arm at Hulk, only for Hulk to dodge his attack and counter it with a right punch to Croc's face, who recoils from the sheer force of the attack. As thick as Croc's hide was, even it couldn't protect him from Hulk's unparalleled strength. Croc and Hulk lock hands as they push against each other, growling like two primal beasts while Batman runs off to collect more of the plant spores. Hulk shoves Croc back, emerging victorious in their show of strength.
"Come on, you overgrown handbag!" Hulk shouts, goading Croc into fighting back. After receiving several more brutal punches from the much stronger gamma goliath, Croc roars in frustration as he grabs Hulk and slams him down onto the wooden platform before trying to bite into his face, only for Hulk to steady himself on a new wooden platform and lift Croc over his head. "Raaaagh!" Hulk roars triumphantly as he tosses Croc against a concrete wall, who then falls into the water again, though he quickly climbs back out and confronts Hulk again, who makes short work of him once again, punching Croc in the face and gut several times before punching out one of Croc's knees, breaking it with a violent 'snap'.
"Ahhhhh!" Croc screams as Hulk punches him so hard, he goes flying into a wall, falling into the water again.
"That injury will slow him down. Hulk, we got enough spores to make the antidote. Let's get out of here." Batman says, returning to Hulk with a vial full of the genetic material.
"You don't have to tell me twice, Bat." Hulk says, more than happy to leave. Croc always creeped Hulk out, despite the several years of experience fighting him.
-Later-
Entrance To Croc's Lair
The two almost make it out until a rusted gate slides down in front of them, trapping them. Croc emerges and roars as he limps towards them. "My caves will be your tomb!" Hulk stands in front of Batman, ready for a fight, only for the Explosive Gel to detonate right as Croc limped across it. The floor collapses, sending Croc plummeting far beneath the sewer floor, cutting him off from his prey as Hulk lifts the rusted gate, allowing them to escape. "I will find you!" Croc roars loudly, though the two heroes paid no mind to his threat.
"Get a hobby, Croc..." Hulk mumbles.
-Author's Note-
Well, now we know what Hulk fears. The fight felt a little short, so I'll update it later.