Aster has long, dark hair and blue eyes. She generally wears a serious expression, but when she laughs, her whole face lights up. She is average height and has a slender build. She leaves her hair loose or pulls it back into a simple braid when she wants it out of the way, such as in potions class.

She is serious and studious. She is introverted and doesn't make friends easily, but is loyal and caring to those she loves. She gets anxious at large social events or when there is too much noise. She is creative, hard-working, and loves animals and the outdoors. Her favorite hobbies are painting, reading, and going for walks. She likes to stay up late, talking with her close friends or reading her favorite books. Her dream is to become a magical veterinarian.

Aster was born and raised on the Gillespie family farm, and loves to explore the Scottish countryside. Her parents were both half-bloods, and Aster has both wizarding and muggle relatives. She has three younger sisters: Rose, Violet, and Daisy. The family lives in an old, stone farmhouse on the shores of Loch Fyne, where Aster and her sisters often swam or rowed on warm summer days, about a 20 minute walk from the outskirts of Inveraray. The farmhouse is far enough from muggle Inveraray that the family can live in peace, surrounded by a muggle-repelling charm, but close enough that Aster and her family can walk to Inveraray occasionally to experience muggle culture and visit relatives from the muggle side of the family. Aster is relatively familiar with muggle culture - her paternal grandfather was muggle-born, and she has several muggle cousins, with whom she occasionally plays football on the weekends.

Her mother, Elise Gillespie, is a healer, and commutes several days a week via Floo to St. Mungo's in London. On days when Elise isn't working in London, she works at home, developing new treatments using plants and herbs. Aster is fascinated by the healing arts, and has already begun to assist her mother with her at-home work.

Aster's father, Albert Gillespie, is a farmer. He inherited the family farm from his muggle-born father, and has dedicated his life to growing both magical and non-magical plants and herbs, many of which either go to feed the family or are used by his wife in her healing potions and tonics. He loves to take Aster and her sisters outdoors, whether it means teaching them gardening, fishing, or simply hiking and observing local wildlife.

Aster is creative, and several of her paintings and drawings are hung proudly on the wall in her half of the bedroom she shares with Rose. Her side of the room is also filled with books, and the floor is often covered in half-finished sketches, unfolded laundry, notes on her most recent area of study, and volumes lying open or with a bookmark halfway through.

The Gillespie family has a cat, two owls, and a half-crup that remained at the farm when Aster went to Hogwarts, and Aster is hoping to purchase her very own owl soon so that she can send letters. Aster will miss the pets (and her family) terribly, but is excited to start her studies at Hogwarts. She is most excited to study herbology, charms, and potions.

Aster's first instance of magic was when she was five years old. She broke a dish while eating dinner, and accidentally made the pieces disappear while trying to help clean them up.