Bluebelle is your Flower Fairy friend, and you rescue her during the Rescue Bluebelle quest, as soon as we reach Level 21. Her house makes fairy vials, which let you craft all sorts of things as you level up into buildings like the Perfumer, Alchemist and Apothecary.
She is also a giver of quests. Her list of quests is below. To see a list of quests given by all characters, please check out the Quests page.