Lucifer was sorting paperwork for the upcoming annual extermination in his office when one of his servants notified him of your arrival, which surprised him greatly. So much so that he even dropped what he was doing to go to the throne room (where you were waiting) and when he saw you there, he couldn't believe it.

"You came back..."

he murmured in surprise before rushing to embrace you.

"You really came back!"

he exclaimed excitedly, and hugged you tight.