Just to preface, I don't know much about Sigma so if this isn't correct or out of character, I'm sorry and I'll try to fix it as a get farther into the anime/ manga. (Also I can't find a gif of sigma so here's one of Fyodor)

(Requested)
Fluff

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What was currently in your possession was a group of cards, each holding its own personal value, the same could be said for the leader of the Sky casino who was seated right in front of you.

'Texas Hold Em' was the name of the game. And currently, you had been winning by a landslide. Fortunately for your current opponent, you guys weren't playing for money.

The Sky Casino head lays down his cards. "Two of a kind." He spoke.

You grinned in delight as you laid down your own cards. "Full house."

Sigma sweat-dropped as he saw your cards in front of him. "I feel like you're cheating at this point."

You chuckled. "You wish. Anywho, I'm bored as hell from all this winning. I wanna do something else."

Suddenly, a large group a voices was starting to be heard through the casino.

"Hey what gives?"

"What the hell? What kind of fuckery is this?"

"These assholes! We'll throw you out of this casino!"

A giant mob of people was beginning to form in the casino. You and Sigma looked at each other is curiosity.

"Are you still bored?" He asked.

"Let's see what this is all about and then I'll give you my answer."

Sigma grabbed your hand and pushed past people to get to the front of the commotion, him in front and you behind. At the centre of the mob, you found two people standing there.

One was a red-haired guy with somewhat formal attire and a top hat on, and the other was a taller brown-haired guy with his arm on the red-haired guy's head.

"Get your fucking arm off!" The red-haired dude nearly yelled.

"Oh but Chuuya, you make for such a good arm rest!" The other man teased.

'So what exactly is the issue here?...'

"What is going on?" Sigma announced. Looking at him, anyone could tell he had this under control and he knew what he was doing, but you knew deep down inside as soon as he saw the crowd form, his heart started racing from the nerves.

Hoards of people gave him answers at to what was going on, and most of what you could gauge was that the two men in the centre have been cheating and causing others to go into massive debt.

"Isn't it your own fault that you got into such debt if you were the ones that gambled that money away?" You ask, your tone being delivered as extremely oblivious and extremely sarcastic at the same time.

Clearly, some were not pleased with your commentary. One man was even mad enough to stomp towards you with a look that could only be described as murderous. "Why you bitch-"

"Hey! Don't touch her!" Sigma shouted at the man with his hand reached out as if to stop him in his place and gave him a menacing glare. The man cowardly backed into the crowd. Everyone knew you two were as thick as thieves. And since him being the head of the Sky Casino meant what he says is basically law, the people with common sense knew not to mess with you.

"You know, I don't think I am bored anymore."

Sigma gave you a look before turning his head toward the two men once again. "As I was saying, cheating is prohibited here. Please refrain from cheating or else the punishment with be at your own expense." Sigma warned.

The brown haired man smiled. "Don't worry. We have already collected everything here that we need to. Bye bye!"

"You mackerel!"

Before you could process what was going on, smoke filled the area. It filled your lungs and you started to have a coughing fit, leaving no room to inhale between each cough, not like inhaling more smoke would make anything better. One of your arms wrapped around your stomach and the other went up to cover your mouth as you hunched over.

From what you could tell, the two men had disappear in the midst of the smoke, not that you payed very much attention to that at the moment.

"(Y/N)! Are you okay?" Sigma asked as he came running over. You couldn't respond to him since your coughing prevented you from doing so. Your knees felt weak and eventually gave out.

"(Y/N)!"

You could hear the panic in his voice. He looked around like he could actually see something through the smoke and carried you to a room that wasn't filled with smoke. He sat you by a wall as he got down and kissed you on the forehead as a goodbye and ran out of the room to deal with the chaotic situation.

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By the time the situation was under control, your coughing fit had ceased and you sat closed-eyed with your back against the wall.

You had heard the smallest creak of the door opening, followed by echoing footsteps. Your eyes remained closed as you heard someone sit down next to you. A few moments of silence passed before opening your eyes and seeing Sigma lost in thought, staring straight ahead yet staring at nothing at all.

"It's okay, Sigma. You don't have to keep such composure around me, you know." You said as you placed a hand on his tense shoulder. That when he let it a loose. He exhaled as if he had been holding his breath for a while, all the more hugging his knees to his chest while placing his head on his knees. You almost laughed at the sudden mood change.

You placed your hand in his hair and brushed through it as he tried to collect his thoughts. His hair — albeit weirdly cut — was soft and silky smooths as your fingers brushed through the strands.

A while after silence and Sigma showing his vulnerable panic to you, he rested his head on your chest with your hand intertwined. You could hear his calm rhythmic breaths, just as he could hear your calm steady heartbeat.

"Are you okay now?" You whispered. Sigma got up and sat on his knees beside you, looking at you like you as if he were mesmerised.

"I think I am." He whispered back. You cupped his face wishing your hands, your thumb grazing over his cheekbone ever so slightly. His heartbeat became fast, and you delicately kissing his nose didn't help either.

"Thanks for keeping me sane, (Y/N)."

You gave him a closed eyes smile. "Thank you, Sigma."

"For what?"

"Being you, of course."

With that, you gently kissed him on the lips while tracing his jawline with your fingers. Although you couldn't see him, you knew he was blushing madly.

You pulled away and took a good look at him. He quickly turned away to his the redness on his face. "Give me a warning next time you do that!"

You laughed. "Okay. If you insist."

He turned around again and saw your face right in front of his once again.

"Well then, can I kiss you?"

He didn't know how to respond verbally, so he answered you with a nod.

You kissed him again with pure bliss, not a care in the world. You had hoped you had helped him relax more from the whole distraction prior, and you had done exactly that for him.

And oh he couldn't be more grateful for you.

<3