Sans is a MONSTER and not a HUMAN, so he doesn't follow HUMAN biology like a HUMAN skeleton. Same with Gaster and Papyrus.  
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James. The guy had been on their minds for awhile, even though it was clear they were trying not to think about it. Since accidentally spotting him on the deck of the ship, Sans nor Frisk hadn't spotted the twin brother of Andrew again. It was somewhat hard to, with the number of people that were actually on this cruise ship. He could probably easily blend into a crowd, and they might not even notice him. "We can't let this ruin our honeymoon." Frisk sighed, as they were sitting at a bar together that was a part of the cruise ship. They had both decided to order small alcoholic drinks, as neither of them exactly wanted to get drunk, but it was still nice to enjoy a little alcohol on their time away from everyone. Sans exhaled.

"it just puts me on edge." Sans admitted, seeing Frisk frown. Normally, Sans wouldn't be concerned. He could take the guy out in one swoop, and it wouldn't even matter after that. But on this ship, with so many people to get in the way... With them being in the middle of nowhere... It was a little nerve wracking. "sorry."

"It's okay... I can't blame you for being nervous. I am too." Frisk lightly told him, as she put a hand on his shoulder and lightly squeezed it. Their situation was a little problematic. If anything went down, it wasn't very difficult to remember they were literally in the middle of nowhere. In fact, that was a detail that kept popping up in their minds in all of this. "But he wants us to feel that way. He's trying to intimidate us."

"i guess so. i just don't want ya to get hurt, that's all." Sans told her, instantly seeing a smile light up her face when he said that. He hadn't tried to be cheesy, even if this whole time together was supposed to be romantic, but he could see how it would come across that way, and that made him grin a little himself. Her smiles were also just so infectious a lot of the time.

"You're so adorable sometimes, you know?" She lightly teased. You wouldn't expect it from someone like Sans. Words like handsome, and cool probably suited the Mafia skeleton better, but somehow he could have moments of being so insanely cute. Him not usually being taken for the cute type definitely made such moments all the more special. In fact, because the conversation had shifted, it was like they were able to forget all about James. He didn't matter, not for now anyway. He should only be an issue if he acted, but until then, this should be all about them, not him. Sans lightly blushed.

"i mean, i wasn't even tryin' to be, but... heh." Sans chuckled, staring back towards Frisk with his own warm smile. In fact, he was almost ready to lean towards her to give her a kiss. She had started to do the same, ready to meet him halfway, until...

BANG. SMASH.

The couple literally jolted in their seats, as Sans' glass that had been sitting in between them upon the bar had been smashed into little tiny pieces, which had cascaded in every direction. What had...? Instantly, Sans turned his attention towards the entrance to the room they were sitting in, and it wasn't difficult to notice... James. With a gun. "shit!" Sans couldn't help but curse under his breath, as another bullet was fired towards them, which only smashed a bottle of alcohol behind the bar.

He had been ready to grab Frisk, so they could duck into cover, but she already seemed to have the same idea, considering she had tugged on his arm to motion for them to move, and the two of them jumped over the bar, keeping them out of danger for a good minute. Even the person who had been serving the drinks had had a good idea to hide behind the bar out of fear, and anyone else in the room either ran, stayed frozen to their seats, or even tried to hide under the tables that occupied the room, (as they didn't only serve drinks but food too).

Looks like James was a problem again now.

"sonofabitch." Sans growled, as he seemed pretty ready to be pulling a gun out of the back of his trousers, which Frisk was pretty surprised by. He obviously had wanted to be prepared for this kind of possible situation. Glasses behind the bar were continuing to get smashed into tiny little pieces by bullets flying through the air, spilling alcohol, juice, and glass everywhere. "stay down." Sans told Frisk, who wasn't really given much time to answer, as he was already getting up with his readied gun, which he aimed carefully at James.

He didn't even hesitate to start pulling the trigger, but of course he had to miss with the first two shots, as James had ran to grab one of the tables, to flip it over onto its side so he could use it for cover. Sans decided to fire several more shots at the table, before he ducked back down into his own cover to reload his weapon. God dammit, why did he have to miss? He could have easily taken him out in one or two shots if he hadn't. Maybe it was about time he started practising his aim again.

"It feels pretty weird to be getting shot at by someone who looks like Andrew, huh?" Frisk lightly laughed, clearly trying to put some humor towards their current, terrible situation. It did bring a small grin to Sans' face for a second, so her joke did exactly as planned. However, the humor was short-lived when they could hear the gun shots going off again from James' gun. "I got an idea." She said.

When she had suggested her idea, at first, Sans hadn't like the idea, because he didn't want there to be a moment where Frisk might put herself out in the open, because she might end up getting herself hurt. But then she said: we're a team. And he couldn't just treat her like she didn't know how to look out for herself. He could protect her, he always wanted to. But he should also keep in mind that she could also protect herself. She wasn't a defenceless woman. She was strong, smart... That was fact.

So, as James was about to start firing again, Sans went to once again aim his gun at the crazy bastard, while Frisk started taking bottles from the bar, only to start tossing them towards James. As this was happening, and James was trying to avoid getting a bottle smashed into his head, Sans began firing his gun again. At this point, James seemed to decide that the best thing he could do is: run. Mistake. One bullet fired from the skeleton's weapon managed to hit him in one of the back of the legs. This caused the human to stumble for a moment as he let out a grunt of pain. But he wasn't done there. In fact, he didn't waste much time to quickly pick himself back up, take his gun, and fire it.

"frisk!" Sans yelled out, as it wasn't difficult to notice his wife getting hit in the shoulder by the bullet, and she went falling over onto the floor. He wanted to help her, make sure she was okay, but then out of the corner of his eye, he saw that that sick freak was trying to get away. It was fine, it was only a shoulder wound. With another growl, Sans jumped over the bar, and went to track down that son of a bitch.

He was going to beat the living shit out of him. He was so livid. Sick bastard. Never did he forgive anyone who tried to hurt him and his wife, especially on their god damn fucking honeymoon. Somehow though, James was very slippery, cause even with a bad leg, by the time Sans had caught up to him, he was on the deck, still trying to run. "GET BACK HERE!" He roared, being ready to shoot him right at the back of the head. But as he thought of even doing that, James had decided to climb over the railing of the ship, and he jumped off. What the fuck?!

Running towards the railing, the skeleton glanced over the edge, to see if he could spot him. But he was gone. He just... Vanished. "fuck!" He cursed in frustration. What the hell had he even wanted?! Had he really just been there to try and kill him? Maybe he was still cold over the fact that his brother was taken from him, and his parents were likely dead too. Motherfucker... Well... There wasn't much he could do now. He was gone.

Now, he should just get back to Frisk, and focus on her. That was more important.