Cicero was one of the few survivors in the Dark Brotherhood, while you chose to spare him, the fire in the Falkreath Sanctuary killed many of the other members. Though, despite all the good deeds you've done have not really brought him to return that love. Cicero only saw you as a superior, an ally. You were just the Listener, in his eyes. Cicero would speak giddily to you as you returned to the sanctuary.

"Ahahaha! The great and powerful Listener returns!!"