Thor released the man from his grip and watched as his body fell to the ground next to Steve.

"We need some oxygen, 100% pure oxygen. This isn't working!" Bruce announced to the others as he monitored Natasha's pulse. Clint was still forcing air into Natasha's mouth.

"He said he was pumping oxygen into the cells earlier, before he replaced it with CO gas..." Tony told Bruce, still staring at the man on the floor.

Bruce ran through the door their captor had used, the urgency with which he moved panicked Tony and he decided to follow. They ran down a long dim corridor; lights flashing as the bulbs died and flickered back to life again. The walls were concrete, like the floors and ceilings; Tony guessed they were in a basement of some sort, but definitely underground.

Bruce flew through the door at the end and quickly started examining countless gas canisters. Urgently pushing aside the ones at the front to get access to the ones behind.

Tony entered a minute later, but his eyes were drawn to the opposite wall; there were photos and news clippings taped to the wall, hand written notes scrawled on them in red marker. Tony's own photo was at the center of the rest, his face circled in red ink. Photos of the other avengers were placed around his; photos of him and Natasha at the cafe they liked, him and Steve walking through Central Park. A photo of Pepper was pinned up; a question mark scrawled over it. Bruce and Thor's photos had large red crosses through them. He'd clearly studied them, carefully decided who to take. It concerned Tony just how much thought and planning had gone into deciding which members of the team would be best used against him.

Bruce seemed to find what he was after as he grabbed a face mask from the shelf and ran back down the hall.
It was an agonising wait for all, but Natasha's eyes eventually flickered open and her breathing steadied. Clint pulled her into his lap and kissed her cheek; slowly letting out a relieved sigh as wrapped his arms around her.
Bruce kept his hand on her wrist; still monitoring her pulse as it became stronger and steadier. He smiled at her reassuringly and took his leave to check over Steve.
Tony went over and sat on the floor, taking her hand in his and whispered a simple statement; "I'm sorry"
She shook her head; told him it wasn't his fault and squeezed his hand weakly.
He nodded but guilt still weight heavily in the pit of his stomach.