Of course Leo Fitz knew how to fire a gun. SHIELD didn't simply allow their agents onto the field with zero combat experience. Sure, FitzSimmons weren't officially cleared for combat prior to joining the Bus, but that didn't mean they were novices. Fitz invented the Night Night Gun with full understanding of a gun's measurements, technicalities and ergonomics. Of course he knew how to fire one.

Shooting someone, on the other hand, was a completely different story. Unlike Simmons, whose first shot at the target board was with her eyes closed, Fitz had fired a decent first round. It actually hit the target. Nowhere near the bullseye, but his hands weren't shaking the way he thought they would. But that was target practice. His minimal experience on Coulson's team had taught him too soon that at some point, he would have to shoot someone. It did nothing for the lead in his mouth.

FitzSimmon's S.O. had once given them an advice that he still adhered to: make a device with which you can point and shoot. Point and shoot, his S.O. always said. Of course, Fitz knew his S.O. meant that advice for FitzSimmons only, knowing that they were shit at trying to shoot people. But Fitz had taken that advice with a pinch of salt and more ingenuity than his S.O. had expected. He applied it in in simple ergonomics. So when he invented the Night Night Pistol, he made damn sure that it was easy as pie for FitzSimmons to handle.

To be sure, Fitz hated having to hurt anyone. His gut was prone to somersaults whenever something was about to happen to someone. There was once when he was up early and he'd seen May and Ward going hand-to-hand on the mats. The mere crunching of muscle against muscle made him squirm and he found his way back to bed extra fast. Another time, May and Ward thought it'd be funny to spar in the middle of the day, right outside the damn lab, while FitzSimmons worked on science-y stuff. Fitz had to soundproof the lab and turn on the music on the speakers. Simmons was distracted the rest of the day and Fitz had resolutely refused to turn his back from the sparring duo. They got very little done that day. Fitz made a request to install two-way tinting mechanisms on the lab door. Eventually.

So when he found a gun by his feet, while May and Coulson fought the Hydra goons at the Hub, he almost wanted to scream. But the logical part of his brain did the math quicker than the conscious part of him realised. Coulson was busy with the Big Bad, Garrett, and May was taking care of another with one coming behind her with a gun. Gut clenching, Fitz grasped the gun, copper bullets and all, steadied his aim despite his shaking hands, and fired four rounds into the goon's back. May turned to him, something like shock on her face. But Fitz had dropped the gun like it was acid, the shake in his hands amplified.

That night, when the whole Hydra calamity was over and done with, and Simmons was washing up in the bathroom, he'd curled into a ball in his bunk, hands tightly clapped between his armpits. They refused to stop shaking. He'd slammed his head against the bunk wall and the pain momentarily distracted him. But his damn hands wouldn't stop shaking. When Simmons came by to say goodnight, she paused at his door.

"I'm fine, Jemma," he said.

"Fitz," she said, and he could hear her heart breaking in her voice, "you've never lied to me. Don't start now."

He looked away, biting his lip, willing the pain to distract him again.

She crawled into his bunk, sat beside him and took his hands in hers. He let her. And for some bizarre reason, the warmth of her palms soothed the ache in his hands. The shaking lessened, until it was the briefest tremble.

She knew. The moment they were reunited after the fiasco, and he'd wrapped his arms around Jemma, relieved that she was alive, she knew. She knew he'd killed someone. They didn't speak about it the rest of the day, Fitz being unusually quiet and jumpy. But Jemma's eyes were an open book and when he looked into those eyes, Fitz knew that she knew. And yet he didn't see judgment.

"Would you-" Simmons hesitated. "Would you like some sleeping pills? I know it's not encouraged and technically we don't know yet if you're suffering from PTSD but-"

"Yes, please," he said softly.

She looked at him, her brown eyes comforting. She patted his hand and left. Came back several minutes later with two pills and a cup of water.

"Here," she said, handing them to him. "Take one for now, and if you still can't sleep, take the other. It should do the trick."

"Thank you."

She turned to leave, the ghost of her comforting eyes lingering on his mind.

"Simmons-"

"Yes?"

"Can't you- Can't you...stay?"

"Oh, Fitz..." she trailed off, pity in her voice. "You know the rules..."

"I know, I know, I know," Fitz replied. "I just..."

The silence between them stretched, Fitz knowing Simmons battling the dilemma in her mind.

"Wait a moment," she finally said.

It felt too long but when she returned, she came with her arms full with a sleeping bag, a pillow and the TARDIS.

"Jemma..?"

She rolled out the sleeping bag outside his bunk, fluffed up her pillow and set the TARDIS up at the head of her pillow. She looked at him, a small smile on her face, "The rules said nothing about sleeping outside the bunk of the opposite sex."

Fitz's smile came easier than he expected it to. He took her hand in his and squeezed lightly.

"Thank you, Jemma."