Steve doubted Natasha had known Schmidt's men would follow him all the way up to her room, so he had to improvise. When they reached the door, he took his time digging around in his pocket for the key card she had slipped him then eyed the men beside him. When he finally did unlock it and it was obvious the men planned to follow him inside, he turned and shook his head at them.

"Miss von Kant won't be happy to hear others have been in her room," he said. One man raised an eyebrow suspiciously but Steve continued before he could object, "She will refuse to work. I will only be a moment."

"Go," one grunted.

Steve hurried inside and shut the door behind him. As soon as it had latched, he rushed to the phone and dialled Tony's number. He had to agree to pay the bill for international calling then waited impatiently for the man to answer.

"Stark." 

"It's Steve." Tony just grunted. "It's an emergency. Natasha needs the formulas DD 13-942 and 13-945."

"What? Why?" He shouted for FRIDAY to turn off his music and the loud background noise stopped immediately. "What exactly is this mission of yours?"

"Look, Tony, I don't have time to explain," Steve answered, but Tony interrupted to ask if they were okay. "We're fine for now, she just needs to formulas."

"Clearly not if she needs the Doomsday Twins," Tony muttered to himself. The nickname did not reassure Steve in the slightest. "Alright, grab some paper."

The first formula was longer than Steve had anticipated and the second one was only slightly shorter. When he had finished writing it down, Tony made him repeat it back to him.

"Good. Anything else?" Tony asked. "You're still near Berlin, right?"

"No, that's all," Steve said, "and yes, east of Berlin."

"Good," Tony replied. "Tell Red to ring if she needs."

He hung up before Steve could ask what that was supposed to mean. 

With only a little time left, Steve hurried to find Natasha's phone and send Fury a short text. Once he pressed send, he stuffed the phone back where he'd found it and grabbed the paper he'd written Tony's formulas on. Stepping back into the hall, Steve pulled the door shut behind him and nodded at Schmidt's men.

"Found it."

He followed them silently back into the elevator and through the lobby.

The car ride back to the base was just as long as before, but this time it was dark. The walk through the base back to the lab was not much better.

If Steve expected a polite escort inside, he was rudely mistaken. Instead, the door was pushed open and he was pushed inside moments before the door slammed shut behind him. With a roll of his eyes, he turned to find Natasha. 

She was already standing in front of him, waiting impatiently for him to hand over the formulas. As she unfolded the paper, she skimmed through the writing then nodded.

"Good," she murmured, smoothing out the paper on the table in front of her.

Turning back to the soldiers, she barked out an order in German and they slowly began bringing her what she needed. Once she had everything she needed, she pulled Steve to her side and began working.

* * * * 

Natasha had finished the first formula by the time the guards were switched out. While it simmering over a burner, she began the second one.

Without pausing her work, Natasha silently tore up the note Steve had written for her. As if she was just tucking her hair behind her ear, Natasha brought a hand up to her face then continued working. It wasn't until the third time she did it that Steve realised she was eating the scraps of paper.

"Eat this," she whispered, handing him some pieces of the paper.

Much less subtly, Steve shoved the paper in his mouth and tried not to make it obvious he was chewing. Natasha continued working, alternating between eating the remaining scraps of paper and finishing the second formula. When the paper was gone, she stepped away from her workstation.

Steve watched her dig through a nearby cabinet before returning with a needle. One of the soldiers immediately protested.

"You're not supposed to use the formula yourself."

Having already anticipated this, Natasha had put aside a compound to set and turn into a jelly-like consistency.

"It's not for me," she retorted, pointing to the jello block.

She very carefully removed the first formula from where it had been cooling and cleaned the needle with a wipe. Dipping the needle inside the beaker, she filled it with the cooled formula.

"What's it do?" the soldier asked, watching Natasha curiously.

In a single motion, Natasha turned her back on the soldiers and inserted the needle into her own wrist. Rubbing the prick mark, she set aside the needle and reached for another wipe to clean it with.

"Attacks the mind," she lied easily, filling the needle just as before. Handing Steve the jelly compound, she met his eyes in a silent question.

Do you trust me? 

Steve nodded once.

As smoothly as she had done on herself, Natasha plunged the needle into his wrist. Immediately, she knocked the jelly compound out of Steve's hands and jumped back in fake surprise, cursing in German.

"Help me clean this up," she told the soldiers. One brought her a towel and she carefully cleaned up the liquid on the floor.

"What did you do that for?" a soldier demanded as Natasha wiped up the mess.

"I didn't mean to," she lied. Her eyes darted to Steve's wrist to make sure the prick mark wasn't obvious and was relieved to find out it wasn't.

"I saw you knock it over," the soldier accused, "right after injecting him with the first liquid."

"Your eyes deceive you," Natasha objected calmly.

While it was clearly the soldier didn't believe her, he didn't press any further. Instead, he watched her even closer as she continued making what Steve now recognised as a third formula. The first one remained where it had been first set, but the needle was nowhere in sight.

When the third formula had been finished, Natasha did inject it into the jelly compound. Shortly after, the block turned from a bright pink to a soft orange and Natasha grinned. Steve watched, albeit slightly confused, as she cut the block into small cubes.

"That doesn't look like something to control people," a soldier said as she plucked a cube from the group.

"It's not," she told him. "It's a snack. Want to try?"

She shoved the cube in the man's mouth before he could respond and he choked as he swallowed it.

"Good?" she asked.

Hesitantly, he nodded and she offered it to the others. One soldier stepped forward and he had just swallowed it when the first man started to seize.

With two of the soldiers down, Natasha quickly took care of the remaining four. She shoved the jelly substance into their mouths and forced them to swallow. Shortly after they swallowed it, each man seized and then went still.

"What is that?" he asked, eyeing the men on the floor.

"Something Tony and I made." Without pausing to look at him, she dumped the rest of the liquid formula down the sink and cleaned out the beaker. "We have five minutes before someone realises they're down thanks to the security cameras."

"The what?" Steve looked around the room. He hadn't seen any cameras, but he trusted Natasha's ability to find them. "What was the stuff you injected me with?"

"You won't start seizing if that's what you're worried about," Natasha teased, giving Steve a short smile. "Makes us immune to any serum or poison gas we may encounter. Now, let's find that data room they were talking about earlier."

They had barely taken a step towards the door when it flew open. A small army of soldiers flooded the room, all carrying weapons that were aimed and ready to use.

"On the ground!"

Steve looked to Natasha.

Rather than follow the soldier's order, she threw herself at the nearest man and snapped his neck before the first bullet had been fired. The reaction was immediate and a dozen guns were fired aimlessly. While Natasha jumped towards her next victim, Steve barreled into the herd to try and disperse them.

Natasha killed three soldiers before the first one got a hit on her. As she moved towards her fourth target, a bullet tore through her leg. She stumbled and let out a hiss of pain as her leg crumpled underneath her.

Seeing his chance, a nearby soldier lunged for her and pressed down on the bleeding wound in her thigh. With a cry of pain, Natasha was forced to stay down as several guns were trained on her.

Until the moment he heard Natasha cry out in pain, Steve had been focused on taking out as many Hydra agents as possible. Everything stopped when Natasha got injured, though. He was distracted long enough that the agents around him were able to knock his feet out from under him and force him to surrender. Only then did his eyes find Natasha.

There was an agent standing above her with his foot on her thigh and after a very quick glance, he noticed she was bleeding. She wasn't complaining and she wasn't gasping in pain, but Steve knew it must have hurt.

Above them, an agent shouted something in German and the men around them pulled them to their feet. They were escorted out of the lab and through a series of hallways and down stairs. In front of him, Natasha's limp grew worse and worse until finally, they stopped in front of a heavy metal door.

Pulling out a ring of keys, an agent in front of them unlocked four separate locks then pushed open the door.

Steve was the first one to be shoved inside. He scowled as he stumbled forward then turned around to demand after Natasha. Before he could argue with anyone, she was shoved into his chest and the door was latched shut.

"That could have gone better," Natasha mumbled, staring at the door as all the locks were flicked back in place.

Steve sighed then looked down at her leg.

"Come on," he said, nodding his head towards one of the beds against the wall. "Let's get that wrapped up."