Abigail has short blonde hair and blue eyes. She has very pale skin, likely as a result of not being allowed to leave her house.
She is a very quiet girl, though she is eager to make friends.
Abigail is revealed to be the daughter of Horace and Clara Dudley. Throughout the entirety of her short life; Abigail's parents seldom allowed her to leave home, fearing the outside world could take her away from them. Though forbidden to leave her home; she would often sneak out, without her parents knowledge, to play with Luke Crain at Hill House. The Crain family believed that Abigail was Luke's "imaginary friend", as no one other than Dudley's had ever seen her.
On the Crain family's last night at Hill House; Luke invites Abigail to a sleepover, which his parents agreed to believing she was merely an imaginary friend. Olivia, having returned to Hill House early, invites Luke and Nell to a tea party in the "Red Room". She also invites Abigail, simply because she happened to be present that night. Olivia had poisoned the tea served to the children. In attempt to have them "wake up" and remain inside Hill House with her forever, Olivia attempts to murder her two youngest children. The poisoned tea is also served to Abigail, who dies upon drinking it.
Abigail's parents find her body in the "Red Room". As they look, in shock and horror, upon her dead body; Abigail’s ghost calls out to her parents. Clara asking who hurt her, she points to Olivia. Upon returning and discovering Olivia's suicidal corpse, Hugh declares that he will burn Hill House to the ground. Horace and Clara beg Hugh to leave Hill House standing, so that Abigail may live on within the grounds. To convince Hugh to decide against burning down Hill House; the two promise to keep the truth of the last night, Olivia, and Hill House from the world, provided that Hugh promises to leave Hill House standing.
"This house; it's full of precious, precious things. And they don't all belong to you." ― Horace Dudley