She is taken into the custody of Cort after her parents were killed in an ambush by a group of Troitan raiders whilst on vacation in Cressia, and because of this, he taught her a few of the Gunslinger's ways and teachings so she would be safe in the increasingly unsafe world, though he made her promise never to tell a soul.
She became obsessed with the notion of becoming a Gunslinger, and began to dress in boys clothing. This made it easier to steal the armory key from Cort so she could train with every type of weapon stored inside. Owing to her training by Cort, she is a remarkable shot, destroying the buffalo skull during target practice. Despite this however she has had a love for Roland Deschain since she was a child.
Role in the Dark Tower SeriesEdit
She is present for the death of Cort where he asks her to remember his teachings so that he will live on through her. She cuts her hair short and binds her chest in an attempt to look like a boy so she can become a gunslinger, freeing Roland from prison. They then find Abel Vannay dead, and then Roland's murdered father. She survives the fall of Gilead and has to flee with the few remaining others.
She shoots an impossible shot that frees the prisoner held by the Cult of Amoco and helps to destroy the cult. During the battle of Jericho Hill she takes a spear through her chest and is thought dead by Cuthbert Allgood.
Roland wakes up at Jericho Hill and discovers that everyone except Aileen is dead, though she has been wounded. She begins to head back with Roland to Gilead, but during a midnight encounter with Not-Men, she dies from her wounds.