A/N: Egads, sorry this is so late, dear readers! Real life has been crazy. Many thanks to RedTigress and Nonyvole of the Beta Branch for their help in this chapter together! Also thank you to everyone who has favorited, followed, and reviewed. :) Without further ado...

Entangled States

Chapter 10

The force of the impact drove the breath from Tony's body. Stars burst before his eyes when his head cracked against the floor a split second later. Time seemed to slow. He lay there for a moment, looking up at the ceiling with the eerie calm of shock.

Adrenaline flooded into his veins as he tried to force oxygen into his protesting lungs. A strangely detached corner of his mind noted the feeling of his heart revving up while he choked and gasped. Pain from the blow to his head and back mingled with growing panic from his inability to breathe. Tony had to brace himself. He knew what was coming; he'd seen what happened when Bruce was injured and the Hulk came out roaring to defend him.

Finally, he managed a shallow breath, and then another, and another. Soon he was panting. An acid tingle he had felt only once before was beginning to spread across his brain. He tried to pull himself up on one elbow. Tony wasn't going to let—

The second blow smashed into him with all the force of a green wave. Tony curled in on himself. Somehow he dragged his body onto its side to try to defend against the flood, but there was nowhere to hide. He squeezed his eyes shut as the Hulk slammed into them. A groan escaped his clenched teeth as green began to flood every aspect of his consciousness. The sear of acid flowed from his head, burning down his neck and spine. His fingernails cut into his palms as his hands clenched into fists.

"Tony!" Bruce whispered. His voice seemed very far away, drowned in the green. "... All right?"

The Hulk roared at the sound of his voice, the impossibly loud sound reverberating through Tony's tortured skull. He yelled with pain, but a choked moan was the only sound that came out. His blood felt like it was on fire. Muscles were rippling all across his body as they made contact with the spreading acid. Suddenly there was a hand on his shaking arm. Bruce, he realized dimly. Only Bruce would be crazy enough to touch him now. A bright flicker of fear pieced through the green fog. No, he had to get away. The Hulk could kill him.

"Get…back!" Tony snapped through clenched teeth. There was a horrible alien quality about his voice, Banner's voice, that terrified him.

The hands released Tony's arm. His muscles, all his muscles, seemed to writhe and shiver of their own accord under his clothes. His skin crawled. His body twisted and convulsed against the hard floor as the monster tried to exert control over Tony's body by force. He was smothering between his brain and the bones of his skull.

Far away, he could hear Bruce's voice. "JARVIS…Agent Barton…"

NO, the Hulk roared, louder this time. Green-hot rage and frustration burned through the engineer. MOVE PUNY HUMAN. Green fingers were ripping through his mind, smashing against Tony's mental knuckles to try to get him to loosen his grip and let the Hulk out. But Tony clung gamely to his consciousness. Another spasm arched his back upward and dragged their head out of his hands. This time he couldn't help shouting with pain. The spasm ended and Tony clutched his throbbing head, gasping during the slight reprieve. Banner's curls were soaked with sweat. He couldn't hold out much longer.

"Tony!" Bruce said. Tony knew he was shouting, but the scientist's voice sounded increasingly distant as he tired. "Have…fight!"

A sick thrill of anticipation blossomed in his stomach. The Hulk sensed his growing weakness. Tony shuddered and his muscles convulsed inwards. His skin was beginning to feel tight. One knee collided with his lip and he tasted blood. He cried out again, out of fear more than pain. He just wanted out of this nightmare and back into his own body. His consciousness was dribbling through his fingers. He wanted to let the Hulk out. At least then he wouldn't have to remember any more of this hell-

No, he screamed at himself over the Hulk's roar of approval. No! If he transformed, he would smash the machine. He would smash Bruce. Damned if Tony Stark was going to let that happen.

He beat one fist into the floor, then the other. Reasserting control over some part of his body encouraged him. The finest of cracks appeared in the impenetrable green murk. His fist hit the floor again and the crack lengthened. The Hulk howled with anger and tried to smother Tony in his head but even he couldn't snuff the tiny ray of hope. Tony forced himself to take a full breath.

"…to focus!" the physicist shouted. He was still too close for comfort, but Tony sensed he was out of arm's reach. "Focus…me. Focus on my voice."

Tony managed to get to his knees before the Hulk sent him sprawling again. He refused to stay down and willed his burning limbs into position. He took a ragged breath and let it out as slowly as he could manage. The hard floor bit into his kneecaps but he didn't care. His fingered splayed on the concrete. He kept his eyes squeezed shut, reluctant to give the Hulk any means of escape.

Boots skidded shrilly across the smooth floor. "The HELL?" Barton's surprised yelp cut through the green haze. "Banner—"

"Wait!" Bruce cried. Tony could hear all of Banner's desperate words now, even if they were still a little…distant. "Just…wait! Tony, I know you can do this. Focus. Breathe first. Just like we practiced. The rest will follow."

He clung to Banner's voice like a lifeline. The words themselves didn't even process; he followed Bruce's instructions without thought or hesitation. There wasn't anything else, besides Tony and the Hulk and his voice. Time had no meaning. His heart rate began to slow. The acid wave receded, leaving his body weak and shaking. Bit by agonizing bit, the Hulk's grip on his mind began to loosen. The green fog dissipated. Finally, the monster let Tony go. Tony slammed his mental door shut after him. Good riddance.

Tony opened his eyes. The workshop lights were uncomfortably bright. Bruce was looking down at him, kneading his fingers together anxiously. His face was crinkled with concern. Stark was too exhausted to even feel relieved. "Please don't make me do that again."

Bruce laughed much more than he should have, giddy with relief and a little bit of pride. He reached down to help Tony haul himself to his feet. His trembling muscles screamed in protest. He hadn't meant it to be funny. But he was Tony Stark, so everyone expected him to make a joke. Especially when things weren't funny. The engineer leaned weakly against a worktable. He reached up to squeeze his temples, feeling utterly drained. Barton peeled himself out of the doorway and strolled over to join them. His bow was slung over one shoulder.

"I knew you could do it," Bruce grinned. The quiet pride in his voice slammed Tony in the gut. The only thing he had done was almost Hulk out. The rest was all Bruce. Tony glanced away, embarrassed. "Are you all right?"

Tony shot the scientist a withering look from under his hand. He released his temples and dabbed at his split lip with his sleeve. Out of the corner of his eye, he saw Barton smirking.

Bruce chuckled knowingly. "Sorry, silly question. Why don't you go take a break? I'll deal with the machine; see if I can figure out what went wrong."

Tony opened his mouth to protest, out of habit more than any real reason. Bruce raised an eyebrow at him. Tony was tired. He shut his mouth and gingerly levered himself off the edge of the table. Barton set his bow down and hiked himself up onto the table nearest the machine. His eyes followed Tony as the engineer headed stiffly out of the workshop. He was hiding behind one of his blank Agent Barton expressions. Tony wondered what he saw.

"You should probably incinerate that shirt," Bruce called after him.

Right, the whole irradiated blood thing. Tony rolled his eyes. Banner was being paranoid; his lip hadn't bled all that much and the reddish smear on his sleeve was quite small. He waved to show that he'd understood and limped outside.

The elevator buttons swam in and out of focus as he selected the penthouse. Tony closed his eyes and sagged against the glass, trying to ignore the disconcerting feeling. The dull throb behind his eyes that had been his constant companion since the accident was building again. He'd hoped nearly hulking out would relieve some of the pressure, but apparently it did not.

The penthouse was blessedly dim and quiet. Tony couldn't bring himself to face the empty bedroom, so he poured himself a glass of water and headed for the couch. He remembered to kick his shoes off before his feet touched carpet. He studied Bruce's stocking feet morosely. Shoes that had been in the workshop weren't allowed on the carpet. Pepper would be so proud that he remembered.

God, he missed her already.

Tony drained the glass in one long gulp and rolled it back and forth across his forehead. It soothed his hot skin. He should probably eat something, but he couldn't summon the energy to get up again. He could barely summon the energy to set down the glass and press Bruce's palms to his eyes. He felt guilty and a little sick.

How did Banner do it?

He could deal with the other voice, the intrusion into his mind, the maddening ache in his head. Even the disturbing dreams, dreams he was certain did not belong to him and had kept him from getting all but a few hours' rest since the accident were manageable. Tony was accustomed to functioning on relatively little sleep. It was the constant, all-consuming fear of transformation that really gnawed at him.

Tony sighed. Bruce was right; it was harder when he was tired and he was so very tired. If anything, the mishap in the workshop today was evidence of that. Tony sensed he wouldn't be able to resist another transformation like the one he had just endured. And god, now Banner actually thought he had a handle on the Hulk. Tony touched the place in his chest where the arc reactor usually sat, feeling skin and bone under his fingers. It was so far from the truth that it hurt. He didn't have control at all, over anything. Not with any certainty.

He couldn't endure it any longer.

He'd tried so hard to do it Bruce's way: keeping his temper, avoiding caffeine, not drinking, trying to meditate, even though Tony hated it and thought it was stupid. But despite these efforts, he felt his already tentative control over the Hulk slipping away as the days passed. If he could just get a decent night's sleep it would help, maybe, but there was no guarantee. So he poured all his energy into the machine, thinking that if he built it quickly enough, it wouldn't matter and he'd be back in his own body before the monster became uncontrollable. But now he simply didn't know how long it would take to get it working. It might take days, maybe even a week, maybe more, depending on how badly the control box had been damaged. Tony didn't think he could hold on that much longer without letting the Hulk out.

Tony trusted his design of the Hulk-resistant room, but transforming here in the city was not an option. He sensed he really needed to let loose in order to tire the Hulk out, and that wasn't happening in the basement of Stark Tower. Asking Bruce to go up north so he could transform without destroying anything important had been his last idea. But Bruce had been right; SHIELD would have been all over them. It would have been a disaster.

He buried his face in his hands. If he transformed, though, it would be a disaster. Realistically, there was no way he wouldn't damage the tower if he went green. Pepper was safe in Washington, but how would she feel if Tony was once again responsible for destroying their home? They always had Malibu, he supposed, but Stark Tower was Bruce's home now, too. Oh god, Bruce. The physicist was right; if Tony went green, the fallout would be catastrophic for him. Even SHIELD wouldn't be able to smooth it over if the Hulk accidentally killed some innocent bystander or a tower employee. Whatever happened would be pinned on Banner and he would have to leave New York. Tony grimaced and the Hulk rumbled at his distress. Tony swallowed hard. He couldn't let that happen. He would not be responsible for driving his friend out of his home, or worse, back on the run.

He couldn't transform again. That was certain. The consequences were too great.

Tony studied his borrowed hands. There was another way; a way to cut the wire to the ticking time bomb that was the monster in his head. He'd thought about it with increasing frequency as the days passed after the accident, and he grew increasingly exhausted.

Bruce had discovered the transformations were physically triggered by adrenaline in the early days of his search for a cure. He couldn't stop that, but with Tony's help and resources, he had managed to synthesize a drug that blocked it from the receptors responsible for initiating the transformation. Just a few milligrams and Bruce couldn't hulk out until it wore off. They'd even tested it, sneaking off to a remote island in the Pacific to try to make Bruce go green. All he got was sunburned. It worked.

Obviously, the physicist insisted on keeping what little of the drug they had left in a special safe in his lab. It was too dangerous to risk falling into the wrong hands. Only Banner, not Tony or even Barton, had the combination. They hadn't even spoken about it in months. Tony sighed. Bruce thought he was the only one who had access, and Tony was cruel enough to let him think that. It wasn't true. He had an emergency override, a back door, which would allow him to bypass any security in the tower. Tony had ultimate control over all the systems, including everything in Bruce's lab.

Tony steepled his fingers and rocked forward so his elbows rested on his knees. Accessing the lab and even the safe was not a problem, but at what cost? Tony didn't have many moral qualms anymore, but the idea of breaking into Banner's lab gave him pause. It was common knowledge that the scientist spent more time there than anywhere else in the tower. Barton said it was because it made him feel safe. To break into his lab and steal the drug…well, the violation of Bruce's trust would do some serious damage to their friendship.

It wasn't like he could just ask Bruce about it, though. Tony knew the physicist would refuse and then he would be on guard for any of Tony's efforts to acquire it. No, it was much safer just to inject himself and beg forgiveness later. He could do it. He had to do it. It was the only way he could be absolutely positive that he wouldn't transform again.

Tony glanced out through one of the penthouse's large windows over the city. He didn't really see the view. The idea of Pepper's sad-but-resigned eyes and a Banner-free tower made his heart twist uncomfortably. He couldn't risk it. There was too much at stake for it all to be riding on his feeble ability to control the Hulk. He was Tony Stark, and Tony Stark would cut that wire without hesitation. He got to his feet. JARVIS said Banner was still in the workshop, so it was safe to head to the lab.

It took him three tries to enter the lab code because his vision was drifting in and out of focus again. Tony glanced warily over his shoulder and pushed the door open. The musical jingle of the chimes Bruce had hung over the door made him jump. The chimes were intended to keep Tony from sneaking up on the physicist. He glared upward at them malevolently as he slipped inside, his conscience prickling. JARVIS automatically brought the lights up, and the controlled chaos of Banner's lab resolved out of darkness.

The safe was hidden in the floor near Bruce's desk. Tony edged around a lab bench and dropped into his chair. He swiveled from side to side uncertainly, biting his thumb for a moment, before pressing a series of seemingly unrelated keys on Bruce's keyboard. The floor retracted, revealing a small safe. Purportedly, it would hold up even in a bomb blast. Tony worried his thumbnail. There was no going back from this. Bruce was going to be beyond furious.

Tony took a deep breath. So be it. There was too much at stake. He couldn't risk it. At least Bruce would be furious in New York. He couldn't leave, not until they'd finished the machine. He'd cool off by then, right?

"JARVIS," he said aloud, the sound of Bruce's voice instead of his own making him jump. It was weird to be in here by himself. "Activate emergency override two thirty-five."

"Voiceprint not confirmed. Further authorization is required."

"Authorization code Stark epsilon delta twelve sigma seven gamma two."

"Authorization confirmed. Emergency override activated."

He held his breath for a moment. The lab hummed to life all around him, computers coming up, the fume hood kicking on, the whine of the vacuum pump on the mass spec increasing in pitch. Tony only had eyes for the safe. The safe door clicked and opened with a pneumatic whine. A set of three small syringes were inside, carefully packed into a rack needle-side up.

"JARVIS, make sure you shut all this stuff down when I leave."

Tony reached inside and lifted one. They were filled with viscous yellow liquid. Absently, he dabbed his split lip with his sleeve. He transferred the syringe to his teeth and pushed one sleeve up past Bruce's elbow. The Hulk rumbled his disapproval. Tony ignored him. He looked down at the syringe. What was left of his conscience begged him to visualize Bruce's face when the scientist found out about Tony's betrayal. But somehow the only thing he could remember was the way Natasha's wary eyes used to follow Bruce around the first few weeks they had all lived in the tower.

He'd show her. He'd show them all. Tony was doing the right thing, not just for him, but for everyone. He gritted his teeth and jammed the needle into a vein.

The wave of nausea as the drug took hold almost sent Stark to his knees. He stuffed the syringe into one of the biohazard containers Bruce kept around just in case and staggered into the hall. He slumped against the interior of the elevator and stabbed a key. The glass felt refreshingly cool where it contacted his hot skin. When he got back to the penthouse he would have to manually erase all traces of his presence in the lab. Then he could sleep.

Tony closed his eyes as he rode upwards. He was doing the right thing. Banner would get over it, eventually.

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