After resetting, a weird glitch happened. The monsters were corrupted by the glitch, or known as "THE DARKNESS." When you made it to snowdin, you encounter sans. Who was corrupted by the darkness. "ĥẹĥ ĥəĥ ĥęĥ... ƴøų ẅæɲñª ĥávɛ ą ɓāð ț-țịmɛ?"