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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Parties. Was it normal to feel this anxious for one? Chara usually liked to think that she was a fairly calm person, she could easily act chill about nearly anything, like everything was going to be perfectly fine. That had been her attitude towards Sans, when he had been crushing so hard on Frisk, and he was acting like it was the end of the world. But as she was staring towards Asriel, seeming to decorate their staircase with Christmas tinsel, she really began to understand what that skeleton had been so scared about. To anyone who thought romance was actually easy, and not the most nerve wracking thing in the world, she was jealous of them, and wanted the skill that she seemed to have lost since gaining feelings for her best friend.

"W-Woah, watch out, Chara." Frisk lightly bumped into the girl from behind, who was standing in the middle of the hallway, seeming to be spacing out towards the goat monster upon the stairs. Frisk was carrying a box of decorations, as her and Sans had actually come around to help decorate, while their children were at kindergarten for the next few hours. Frisk smiled knowingly, while Sans the skeleton lightly budged past the two to go to one of the next rooms of the house. "You're spacing out a little there." She teased.

"No I'm not! I'm fine!" Chara hissed, growling so loud that the two girls ended up catching the attention of the confused goat who was standing midway up the stairs, being basically almost finished decorating the railing for the stairs in tinsel. 

"What are you fine about?" Asriel questioned.

"Nothing! I just thought Chara was feeling a little under the weather, that's all!" Frisk stated, before going to try and push Chara towards the living room. "We'll just be decorating the living room." She said, leaving the bewildered goat upon the stairs, who after a small shrug of his shoulders only continued decorating the stairs. Chara could have snarled at Frisk, due to the worry that the girl could have almost blown her cover and her secret, but Frisk only told her to relax, as they began decorating the living room together with Sans - who had already started on putting tinsel in various places.

"romance isn't so easy after all, huh?" Sans grinned towards Chara, who could only grit her teeth and clench her fists. She did not enjoy being teased like this, which was very clear. If she wasn't worried about Asriel hearing, she probably would have yelled for Sans to shut the fuck up, as her whole face was already becoming as bright red as a strawberry. It wasn't easy for her, with her attitude, having a crush... Because she just wanted to act calm, like Asriel didn't totally cause her heart to go utterly crazy within her chest whenever he was around. But that wasn't the case. 

Especially during the actual party.

Chara didn't know why she was expecting Frisk to tell her what she was going to be up to with Sans, what her plan was going to be to try and get her and Asriel together, because that didn't end up being the case. Frisk only told her that it was a "surprise", and in all honesty, that only made her more scared than excited. It had been hard not to keep thinking about it, even when she was allowing various guests in through the door. What were those two up to? Even when she was watching them interacting with various other people, like Undyne, or Papyrus, or Mettaton, or whatever... She couldn't stop questioning: what were you doing? 

"Hey, auntie Chawa! Can you play with us?" Luna was suddenly at her side, seeming to tug upon her pants leg, while Leo was also with her. To tell the truth, Chara felt more invested in keeping an eye on the couple who she was very suspicious of, as she spotted Sans talking to Asriel as they went to the kitchen. Chara sighed, looking back to her niece and nephew, only to smile and nod as she agreed to play with them. The two children cheered, before seeming to break into a game of tag. Leo started it off, by tagging Chara, and then the two ran away, laughing and giggling. She felt like she was too old for a game of tag, but of course she would humor them, for their sake. 

It was quite a laugh, actually. Running around after them, (while trying to avoid running into other people, like Grillby for example... She would have hated to accidentally spill his drink on him...), like they were obstacles, in an obstacle course. It just made Chara think how simple it was, to be young. Sometimes, she missed being a little kid, growing up with Asriel. At least back then, she wasn't aware of these stupid annoying feelings, that could possibly change their friendship forever if she even decided to act out on them. The last thing she wanted was to ruin what she had with Asriel. As long as she got to remain in his presence for as long as possible then... She was okay with at least that, rather than losing him altogether.

"Oh, no, guys, not in the kitchen!" Chara yelled after Leo and Luna, who were giggling and laughing, as they sprinted into the kitchen together, causing Chara to follow after them. Doing this, she discovered Sans and Asriel in the kitchen, seeming to have a conversation, until it was interrupted by the two giggly children who hid behind Sans' legs. "Not in the kitchen guys..." Chara sighed once more. 

"oh, sorry about that." Sans stated, looking down towards Leo and Luna. "come on ya two. if you're gonna play, don't do it in here." Sans went on, before continuing, saying he'd lead them back to the other room. And that's exactly what he decided to do, as he shooed the two children back towards the living room, leaving Chara and Asriel alone in the kitchen. Asriel laughed a little at the fact that Chara seemed out of breath, while holding her hands on her hips in the process.

"Are they being a bit too much for you?" Asriel joked, while Chara rolled her eyes. 

"You could say that again. I definitely do not have as much energy as those two." She breathed, even being someone who was in the Mafia, if she had to chase those two down for a mission or something, she bet anything that they could run forever, while she would be trying to catch up with them, huffing and panting like an unfit dog. She exhaled. "What were you and Sans doing in the kitchen anyway?" She wondered, changing the subject, while she continued to catch her breath. She wondered if this was all put of his and Frisk's stupid plan. 

"Not much. We weren't really talking about a lot, he just said he wanted something to drink." Asriel said, glancing towards the glass that he had decided to leave behind him on one of the kitchen counters, after seeming to usher out the kids. Asriel rose a brow in confusion. He hardly touched any of it, and just left it there to sit? That seemed like a bit of a waste... Even if it was only orange juice... "Anyway, we should probably go back into the other room." Asriel stated, and Chara nodded in agreement, going to be the first to turn around on her heel to head to the other room, with the goat closely following behind. That was, at least until she noticed something that made her feel like she wanted to have a heart attack. She stopped in her tracks within the kitchen's doorway, causing Asriel to lightly bump into her back. 

"What? What are you--?" Asriel was speaking in confusion, until he seemed to notice it too. Chara couldn't believe it. Un-fucking-believable. She knew that it hadn't been there before, but somehow, in all of this, Frisk had seemed to put what appeared to be mistletoe, on the top of the doorway. How stupid. This was just embarrassing. Like Asriel was just going to want to kiss her, just because they found themselves falling for this stupid, fucking ridiculous trick. Who said she had to go through with it? She could just laugh it off, and say how dumb it was. She was almost close to doing that, at least until she saw Asriel's embarrassed face. 

"What? It's not that big of a deal. We can just ignore it." Chara nervously laughed, really wanting to get out of this situation. It was too much. Even if her words heavily contrasted with what was going on with her heart right now, she just needed to get out of this. There was no way... But then she saw what appeared to be a hurt look on Asriel's face, and that surprised her. "What?" 

"...N-No, it's nothing. You're right." Asriel was almost ready to walk out from under the doorway,  at least until Chara grabbed his arm to stop him. He glanced back towards her in shock.

"No, what? It's clearly not nothing." She had hated to see that look of disappointment on his face. That look that clearly showed he had been bothered by what she had just said. It might have just been part of her imagination but... She hated to see Asriel look bothered, especially because of her. She thought for a moment, strongly hesitating as she kept a hold of his arm. She bit down on her bottom lip, feeling extremely nervous. "Did you... Did you want to kiss me or something?" Chara wondered quietly.

"N-No! I-I... I mean..." Asriel stammered, until exhaling in defeat. He had wanted to tell Chara how he felt about her since forever. So, what better chance was there to do so, other than right now? He could stumble, and stutter over his words all he wanted, but there was something that he couldn't deny, and that was just how he felt about her. "Maybe... Yes." Asriel admitted honestly, staring down to the ground, so he ended up missing Chara's eyes widening at his statement, while a bright red shade of blush clouded over her cheeks. 

Asriel wanted to kiss... Her? But... He saw her as family, didn't he? Surely, that's what she thought, that he would just see her as a sister, or as his best friend, or something. She thought that never in a million years, would she be lucky enough to be able to fall in love with her best friend, who she had known for such a long time. After all, everyone around her was getting lucky, ending up with people who they wanted to be with. Who was to say that the world would grant her exactly what she had wanted, since realising how she felt for this silly goat? She sighed. He really cared about her like that? Was she not just stupid for thinking that he would? What if this was a dream?

Well, even if it was a dream, she might as well try to make the most out of it. Deciding to step on her tip toes a little, (seeing as Asriel was somewhat taller than her), she managed to catch his attention, as she neared her face towards hers. "You should have just told me..." Was all she said, until she pressed an extremely hesitant kiss to his mouth. In all honesty, Chara had wanted it to be a little more romantic, or at least a bit more forward, but all she was doing was kissing like a pathetic, scared school girl.

Thankfully, the goat didn't seem to mind, as he lightly wrapped his arms around her, and he romantically kissed her back, right under the mistletoe. From the living room, Sans and Frisk could only smile as they watched, being able to see what was happening from the doorway to the living room. Even Leo and Luna were watching, quietly giggling among each other, as playing tag to lead Chara to the kitchen had all been part of the plan. Even Sans was glad, glad that he could repay Chara a favour, for all the times she had helped him when he was helplessly in love with Frisk. Just, seeing how much they obviously cared about each other...

It was extremely cute.