You've wandered for a while, preying on innocent monsters until you've stumbled into Waterfall. You now sit on the water's edge surrounded by an eerie silence. You explore this mind some more. Memories of a tall monster with gills, the name Undyne flashes by. You keep pushing. More monsters, all helping this body survive the underground in the past game. Still not what you're looking for. You find a small memory of the short Skeleton. He's sitting behind a wooden stand, smiling at you and talking about something. You pay closer attention to hear the conversation.
"I've never seen the stars,kid. Are they cool?"
"Yeah, they're pretty bright."
"You're pretty bright,too."
She laughs, "Yeah?"
He just stares at you with a sort of wonder, smiling.
You push further, finding another. They sit in a small food establishment, laughing and making jokes. They're discussing pranks they could pull. The skeleton laughs and places an arm over the girl's shoulder. She feels warm. He suggests something a bit too cruel for this girl's humor, she laughs and says "No, Sans." A wide grin spreads across your face. Sans. You have this clown's name now. You stand and walk across the flowers of the water, which have already been conveniently pushed into a path by twisting vines. Asriel has been helping you, but you've payed no mind to him. He'll serve his small purpose, and you'll slay him too.