When you fell into the underworld, you were given the power of reset. You lived many lives and got good at fighting, but retained no memory. Your fate intertwined to cross paths with Sans and Papyrus everytime. The only person aware of these resets was Sans. He couldn't tell how he felt about you. In some lives you were kind, others merciless. Not like you remembered any of it. What he couldn't understand now was why this time it seemed you were flirting. Slowly you too would regain your memory.