Alice is the niece of a witch who in the first book of the Wardstone Chronicles is under the care of her Aunt, known as "Bony Lizzie" by the locals because she uses Bone Magic. She first tricks Tom into freeing the witch "Mother Malkin" but helps him escape from her Aunt. She originally came from Pendle. Her mother was a Malkin and her father was a Deane, though neither practiced witchcraft. They died at an early age so Alice was put under the care of her Aunt. It is later revealed during the 5th book that she is the daughter of the Fiend and Bony Lizzie, the Fiend himself telling Tom this.
In the first part of the Wardstone Chronicles, Alice Deane seems to be a confused young girl seemingly under the wrong influence. However, as the series goes on, she starts to see from good and bad, even though she still uses dark magic, and starts to help Tom in many ways. She seems to be a feminist, throwing a fit when Tom suggested that she cooks. (Although Tom later pointed out that she is good at it.) She also seems somewhat reluctant to help out Mr. Gregory when he's in a tight spot, pointing out that he probably wouldn't do the same for her, but ends up being convinced by Tom to do so anyway. She doesn't like the fact that Mr. Gregory doesn't trust her, and is known for throwing fits when she's left out of something big. She claims Tom's mother left her with instructions to protect Tom by any means, which she uses as an excuse to try and use the dark as a tool.
However, Tom's mother was often worried about how Alice would turn out, as she seems to be on the fine line between good and evil. Even though she helped destroy Mother Malkin and the Bane, it was (mostly) her fault that they had to be stopped in the first place, albeit unknowingly. Bony Lizzie had made her convince Tom to give Mother Malkin blood cakes, and she had made a sacrifice to the Bane out of pure hatred and spite toward the Quisitor. Although she knew the consequences, she had freed the Bane to help Tom, Mr. Gregory, and herself.
Alice seems to have a gift with botany, putting leaves on Tom's hand to treat his burn and mixing a potion to help Mr. Gregory's pneumonia. She is assigned to tell Tom all she knows while she is staying at Chipenden, as well as copying Mr. Gregory's books. Tom said that she had nice handwriting at the end of the book.
During the books, Alice is said to be pretty with big, brown eyes and long, black hair. She seems to have feelings for Tom as she jokes about using, during a moment of solitude during the day of his birthday, glamour and fascination on him, two witch powers to seduce him and often control him. Another reason for believing that Alice has feelings for Tom may come from the fifth book, where she is tormented by the idea that she will be separated from him and eventually kisses him.
At the end of the fifth book, Alice contacts Grimalkin (a savage witch assassin) to help Tom defeat the Fiend's daughter, Morwena, which later gets her banished from Chipenden. She revealed to Tom that she was going to become a witch once back in Pendle Hill, claiming that's where she belonged.
In book 6 Mab Mouldheel tells Tom she has 'seen' the death of Alice Deane, saying the a Feral Lamia will have her in its jaws and take her to it's lair and drain the blood out of Alice then her heart will stop. But what happen's when the time comes is that Tom uses the dark wish given to him by Grimalkin to save her.