Requested by @Qichu123, who wanted a yandere Frans involving cheating and some music. (Something that I procrastinated on.)
"Frisk, Frisk, Frisk, wait!"
When Frisk had met Lucas, she had been charmed by him. He was a musician at her college and shared her art classes. He brought her lunch and dinner when days and nights at the Embassy grew long. They had moved in after two years of dating and after his first album release. He was sweet and had a natural charm that could match Papyrus's. She was so sure that they were going to be married one day.
But now...
"Frisk, I swear to the stars, it's not what it looks like!" Lucas said desperately, grabbing her shoulder. She snapped away, glaring at him. He held up his hands in a gesture of peace. "I promise you!"
She raised a brow. "Really?! Because it looked like you were making out with another girl when you were dating me!" The club music could still be heard from out here. The pounding bass and loud rock lyrics were giving her a headache. "So, tell me Lucas," she took a step forward. He stayed firm. "What is your explanation?"
His look was firm. "Sans told me that you were looking for me and that you were standing over there." He ignored how she paled. "You know how dim MTT's lights can get and under them, she looked like you." A worried expression crossed Lucas's face. "I think she was a little drunk, which was probably why she didn't immediately slap me."
Sans.
Sans had apparently misdirected Lucas.
Everyone in Frisk's family had taken time to warm up to her boyfriend. For Undyne and Papyrus, his lazy air made it seem that he didn't have the energy to put in a relationship and Frisk would be stuck doing everything. For Mettaton, it was because Lucas didn't watch his movies and Alphys had issues with his dislike of anime. Toriel and Asgore had issues with the lazy air, the fact that he was going to become a musician- an unstable career choice, and the simple fact that he was taking Frisk away.
Sans had been the worst. What his problems were with Lucas, he refused to say. But everyone else had gotten over their issues to bond with her boyfriend. Sans had refused to warm up to him. Papyrus had assured Frisk that it was a simple issue of laziness.
But if Lucas was saying was correct, then...
No.
"There is no way Sans would do something like this." she snapped. Lucas gaped. "Don't make up lies to protect your own arse." Frisk turned and walked away, leaving the musician standing there. She couldn't help but throw one last shot over her shoulder.
"I'll be out of the apartment in two days."
-_-
"Shame what happened with Lucas," Sans said lightly.
It was a week after Frisk and Lucas's breakup. He had been sending her a few texts, pleading for a chance to talk. He seemed to have gotten the message at her silence since he hadn't sent her another message in two days.
"Yeah," she said quietly, staring at her tea. They were watching MTT on TV. Frisk had been staying on the skeletons' couch since her parents were currently on a cruise. She gathered her courage and looked up. "You know something? He said that you told him that the girl he was making out with was me."
There was a moment of silence.
"Really?!"
"Yeah!"
Sans chuckled. "I mean, I had an issue with the guy, but I didn't know he was a liar!" He raised a hand up to his mouth to stifle his laughter. The movement made her notice a stain on his sleeve.
In the dim light of the TV-lit living room, it looked like ketchup.
