Leone is a sphero that works for Ker'aooc. In LBA2, Twinsen meets her in the pharmacy, and when the thief steals her umbrella, he gets it back. In return, Leone tells him to go see Ker'aooc in Desert Island. From then on, she is always seen working in Ker'aooc's house.
It's possible for Twinsen to take course of actions that will dispel the storm before meeting Leone, or returning her umbrella to her. In that case, Leone doesn't tell him about Ker'aooc, but rather learns about him from Zoé.