A/N: I don't really have an over-arching plot yet – so far I'm just having some fun.

Disclaimer: I don't own Marvel's The Avengers

Chapter 3: Making a Switch

An eerie voice spoke inside of Tony Stark's mind. It sounded ancient, inhuman, and highly amused.

"Someone once asked you what you'd be without your suit of armor. I remember laughing at your response. 'Genius, billionaire, playboy philanthropist,' indeed. I wonder what you'll be now that you're none of those… well, except for genius, I suppose. Oh, I haven't had this much fun in ages!"

The voice disappeared, and Tony Stark opened his eyes. Wherever he was, it wasn't anything like the tidy, sterilized lab in which he had been a moment before. Tony was in some kind of cave, rock walls enclosing him on all sides and a low ceiling with stalactites jutting down at him from above. There seemed to be electricity, however, and the cavern was filled with metal parts and work-benches littered with soldering-irons and welding equipment. Something about the cave and the make-shift workshop was giving Tony extreme déjà vu. Though he had no clue as to why, this cave felt as familiar as the back of his hand.

"Ahem," a weak cough made Tony swirl around, wishing he had his Ironman suit on to react to the threat. He realized two things at the same time: first, he had been wearing his Ironman suit just a second ago, when he had been in the lab; and second, the man who had startled him was someone he knew. Correction – someone he had known.

Because as far as Tony Stark knew, Dr. Yinsen was most certainly dead. He'd died several years ago, sacrificing himself to buy enough time for Tony to activate the prototype Ironman suit. It was all thanks to Dr. Yinsen that Tony had managed to escape from the terrorists who'd captured him, and it was thanks to Dr. Yinsen that Tony had sworn never to make or sell weapons ever again. Wait…

Tony looked around the dark interior of the cave once again. He was right… he had seen this place before. This was the workroom in which he'd crafted the first version of the Ironman suit! Tony looked at Dr. Yinsen in astonishment. The Tesseract had sent him back!

Dr. Yinsen was looking at Tony as if he was a ghost, which was exactly how Tony felt himself. The doctor approached Tony warily. "Who… who are you?"

Wait… what? "Tony Stark, obviously," he replied. "Can't you tell from my good looks, charm, and signature facial hair?"

Dr. Yinsen scratched his head, puzzled. "Well, that's just it. Tony Stark was just here. He was about to activate that suit! But you, sir… you are not Tony Stark." He pointed to the metal man waiting on a stand against the rocky wall.

Tony had to wince when he saw it. Admittedly he'd been a bit rushed when he'd made it, but seeing such shoddy workmanship was simply embarrassing. How he wanted the Mark 7 back, which homed in on his tracking bracelets. That suit had been sleek and sexy… this one was a rusted hunk of junk. Definitely not his finest work.

But Dr. Yinsen's words broke through Tony's self-critical appraisal. "What do you mean I'm not Tony Stark?" he demanded. "Of course I am! Who else do you know who has pieces of shrapnel stuck in their-" he pounded his chest for emphasis, but his hand hit only solid flesh. Tony froze.

Before he could do anything, the sound of shouting echoed through the cavern. It came from outside the little iron door, and it sparked a deep dread in Tony. He knew exactly when this had happened before, and he knew what happened next.

Sure enough, Dr. Yinsen hefted an AK-47 that had been lying on a nearby workbench. "Whoever you are, and however you got here, it seems that you know who I am. Can you operate that iron suit?"

Stark nodded. Dr. Yinsen grinned, taking Tony's apparent physical transformation in stride. "Then at least one person is getting out of this godforsaken place alive. The suit will take a few minutes to become operational. I can buy you that much time, at least."

Then Dr. Yinsen ran off, slamming the door behind him. Tony only had time to yell after him, then the doctor was gone… for the second time.

Tony yelled in outrage and confusion. Things were happening too fast… what was going on? But if this was like before, the only way for him to survive was to activate the Ironman suit and fight his way out. Then he would be rescued in the desert by Colonel Rhodey, just like before. But Dr. Yinsen was still going to die.

As Tony walked over to the suit, he felt a deep anger welling up inside of him. It was seeing Dr. Yinsen again that brought it up, and being helpless to keep him from sacrificing himself once again. As the fury washed through him, Tony began to feel strange. There was a coursing through his veins, and then a feeling of heat that quickly escalated to actual pain.

Just as the pain became a shooting agony, Tony drew close enough to see his reflection in the rusted metal of the iron suit. It was not the face of Tony Stark, internationally renowned inventor that looked back at him. It was the face of Bruce Banner.

Oh… oh dear.

That was Tony's last recognizable thought as the transformation began, his muscles swelling and his skin taking on a greenish hue. His mind was pulled under by the wave of rage sweeping through him.

Outside in the corridors, the terrorists approaching Dr. Yinsen heard a terrifying roar. It shook the ground beneath their feet and turned their legs to jelly. They stopped in their tracks, too afraid to take another step.

Dr. Yinsen had a vague impression of something large and green running by him, and then he was pushed aside almost carefully by a giant hand. He screwed his eyes shut, praying to get out of this in one piece. The terrorists began praying as well, calling to Allah to deliver them, but from the sound of their ensuing screams and the earth-shattering roars of the Hulk, it didn't seem like their prayers were being answered.


Bruce felt a rush like an electric shock, and then found himself somewhere completely different from Eric Selvig's laboratory. He was in a bedroom, lying on a bed. He was also completely naked. Bruce pulled the soft red blanket up around his chest, desperate for some sense of security. What the hell had happened?

He always lost his clothes after the… other guy came out, but Bruce could have sworn that he was in control when Thor disappeared! He was much better able to control his ability, and even if he didn't remember what happened while he was transformed, he always remembered what led up to it. This time there was nothing – only the Tesseract seeming to explode, and then… here. Wherever here was.

There was a creaking sound, and Bruce looked up to see the door to an attached bathroom swing open. He clutched the blanket tighter around his body, senses on alert and ready for a threat.

The door opened fully, revealing a gorgeous red-headed woman wearing… well, practically nothing. She had slinky black lingerie with little frills, and she posed in the doorway with a provocative smile.

"Uh," Bruce stammered, "who are you?"

She gave him a confused look. "What? What are you talking about, Tony? You know who I am."

Now Bruce was very confused. "Tony? But my name is Bruce… Bruce Banner."

"That scientist who turns into a green monster?" the woman asked, looking as confused as Bruce felt. "The one they call the Hulk?" Then her face lit up with comprehension, and she looked at Bruce with wicked speculation. "Tony, I wouldn't have expected this from you… are you trying to role play right now?"

Bruce could only stutter, the words driven right out of his head by the drop-dead gorgeous woman now advancing towards the bed, her hips swaying provocatively with every step. "Let's see," the woman mused, tossing her hair to one side, "who should I be instead of Pepper Potts? I could be a librarian, but I've left my glasses in the other room."

It was the name Pepper Potts that finally made everything click into place for Bruce. He remembered Captain Rogers once asking Tony if he had a girlfriend, and Tony replied that he was in love with a woman named Pepper Potts. It wasn't the kind of name you forgot easily, and Bruce doubted there could be two women with that name.

Wait… Pepper had called him Tony! Bruce looked down at his hands and arms. They were subtly different from his own, a little hairier and less muscular. His hand shot to his face, where he encountered a prickly and all-too-familiar moustache and goatee. Bruce let out a terrified eep and bolted from the bed, remembering at the last second to grab a pillow with which to cover his manhood.

He ran past Ms. Potts, who was watching him now as if he had truly gone bonkers, a possibility which Bruce wasn't willing to rule out just yet. Bruce slid into the bathroom and risked a look into the mirror. It was Tony Stark's face that greeted him, for once without its perpetually smug expression. Bruce couldn't help it – he screamed like a girl.

"Tony," Pepper said with exasperation, "or Bruce, or whoever you want to be… this is a little strange. Are you ok?"

Bruce walked back into the bedroom, clutching the pillow with a death grip. "I'm, um…" he said, thunderstruck. "I'm fine…"

He wasn't even sure what nonsense his mouth was spouting while his mind tried feverishly to understand what was happening. Was this the Tesseract's doing? What else could possibly have resulted in him inhabiting Tony Stark's body?

Pepper went to sit on the bed, patting it suggestively. "Then if you're all right," she said, arching one eyebrow, "come back to bed."

The increasing pressure against his pillow reminded Bruce that it had been a long, long time since he had been with a woman. Since he had been alone with a woman, for that matter. His… condition… made anything beyond flirting extremely risky, to put it mildly. But here was Pepper, and she clearly had no clue that he wasn't Tony Stark…

No! What was he thinking? Bruce would have hit himself in the head, but he had to keep a tight hold on his pillow. How could he even think about that? Tony was his teammate, for heaven's sake!

Well, said a sly little voice in Bruce's head, Tony does kind of have it coming. Did he or didn't he trap you in an outhouse for eight hours while flying from India to New Mexico? Really, it'd be nothing more than he deserves…

Bruce squashed that voice as firmly as he could. Teammates did not sleep with each others' girlfriends! Bruce had principles, damn it, and he wasn't going to abandon them even if Tony Stark was a colossal prick and his girlfriend was a goddess in human form.

"Shit, Pepper," Bruce said, inwardly cursing at himself for having morals, "I can't do this right now. I, um… have a headache?" he finished lamely. He was going to have to figure out what was going on and fix it quick – but first, he would need to find some clothes. The pillow wasn't going to last much longer.

Bruce walked out of the bedroom into the living room, searching for Tony's clothes. Pepper's disbelieving snort followed him out.

Bruce couldn't help but sigh with regret. Damn you, Stark! He shouted inwardly. You owe me big for this!