At one point during Link's adventures, Orielle flies off to investigate Fun Fun Island and does not return. Concerned, Parrow asks Link to search for her. When Link returns with news of her status, Parrow gives him a bottle of Mushroom Spores to heal her injured Loftwing. When Link does so and returns to Parrow, he allows Link to keep the bottle, and also produces five Gratitude Crystals.
Later in the game, if Link speaks to him, he mentions how he has not seen Groose, Cawlin, and Stritch around town lately, and says how their defeat from the Wing Ceremony must have made them stop playing around and get serious.
An interesting fact is that a loose Gratitude Crystal can be found in a corner of Parrow and Orielle's house.