- "I know many things. I know how to communicate with the spirits, and I know things about people that they don't tell me. Call it intuition or ESP."
- —Abby to Nancy
Abby Sideris is a suspect in Message in a Haunted Mansion.
A woman who appears to be in her early thirties, Abby is well-groomed and in good health, sporting a trim figure, pale skin, and an angular face. Her hair, which is slightly curly and reddish-orange, flows past her shoulders, reaching her middle back, and her eyes are a very pale shade of hazel.
During gameplay, Abby can be seen wearing a lavender sweater buttoned over a white turtleneck. A brown belt loops around her waist, accompanied by a long black skirt that reaches her knees. Her ears bear large golden hoops, and her nails are painted blood red. While conducting the seance, she wears an oversized purple turban with an ornate red jewel in the center.
To an almost unhealthy level, Abby lets her beliefs dictate her everyday mannerisms. Almost the minute she meets Nancy, she is ready to jump into a spiritual discussion, exposing her avid belief in the supernatural. She can be quite intense about these beliefs, prone to mood swings when the supposed ghosts of the house are mocked, and often tells outrageous stories about the spiritual realm, claiming her ghosts to be behind the mansion's recent accidents.
Despite her somewhat eccentric beliefs, Abby is considerably charismatic, using high language and smooth words to display a sense of intelligence and understanding. As richly vocal as she can be, Abby is often unable to fulfill her picturesque words and can be somewhat lazy, as the seance she plans is soon uncovered as a hoax, and Rose, her friend and fellow housemate whom she met in River Heights, continually scoffs at her inability to stick around whenever chores need to be done.
Abby's aspirations are high, but she is unwilling to do the work that needs to be done, often annoying Rose. Abby can be very secretive, leaving the house at odd intervals and spending the majority of her time in her room. She is also quite the deceiver, setting up false hauntings around the house in order to attract publicity. This almost maniacal motivation to convince others of her beliefs requires Abby's every attention, as it includes an intricate setup in her room and even tolerance of Rose's disdainful comments. Above all, Abby places her priorities in the supernatural, sacrificing diligence and honesty in doing so.
When frequent accidents begin to plague the budding bed and breakfast of Abby and Rose, Nancy Drew is called to the scene to investigate. Once there, she meets Abby, who warns Nancy that she can sense an aura of danger around the young detective. She then correctly comments that Nancy doesn't believe in ghosts. Impressed by Abby's foresight, Nancy asks how she knows such things, to which Abby laughs and claims to know many things about the spiritual realm. She then warns Nancy to watch out for resentful ghosts who may give her a hard time for not believing in them, in particular a ghost by the name of Valdez.
When Nancy mocks Abby for her belief in ghosts, Abby's anger sparks, and she cautions Nancy that the supernatural can do considerable harm to those who don't believe. Without waiting for an answer from the doubtful Nancy, Abby excuses herself, informing Nancy that the evening will reveal more about the mansion's ghostly residents.
Through Rose, Nancy learns that Abby and Rose purchased the mansion together in the hopes of converting the old house into a bed and breakfast. Some old papers were found by Abby in her room and kept on a chair in the parlor. At some point before Nancy's arrival, Abby and Rose tried to solve a tile puzzle in the dining room but gave up after it proved too complicated, prompting Nancy to finish it for them.
Not long into the game, Abby hosts a staged seance, pretending to have contacted the spirit of Diego Valdez, but neither Rose nor Nancy leave impressed. Rose even goes so far as to tell Abby to stop playing games, as there is much work to be done around the mansion. After the seance, Nancy investigates the basement, discovering a projector and speaker in the base of the seance table.
When confronted about the staged seance, Abby remains adamant in her beliefs, claiming that seances will make a good attraction for the mansion. She also discusses the old papers with Nancy, expressing her hope to have them framed and put on display.
At some points during the game in which Abby is out of the house, Nancy snoops through her room, revealing Abby's taste for color and myth. The young sleuth also discovers an entire system of staged haunting devices in Abby's room, including a two-way mirror and recordings set up to play around the house.
After Nancy discovers Valdez's treasure, Abby and Rose are rewarded by the bank whom the coins belonged to for finding the treasure. With Louis's schemes uncovered, the mansion continues renovation as normal, and news of the recent gold discovery draws visitors in from all around, jump-starting the bed and breakfast's success.
The library search engine lists Abby as having wrote a book called Seen but Not Heard.
Unlike Rose, Louis does not scoff at Abby's belief in ghosts but instead finds the theory intriguing and altogether plausible. Similarly, Abby recognizes Louis's experience and hails him as a helpful and reputable antiques dealer.
Despite Nancy's adamant disbelief in ghosts, Abby is bound and determined to convince Nancy of the existence of human spirits, tolerating the detective's many sarcastic comments in regard to the supernatural. Though mostly respectful of Abby's superstitions, Nancy occasionally lets her true opinion slip, revealing her doubt in such a cause as ghosts. The two generally get along, only arguing on the topic of the supernatural, with Abby opening her advice and expertise to Nancy, occasionally deceiving her with faked hauntings.
Abby first met Rose through the drama program at River Heights, where Abby served as a drama coach and worked on a number of plays with Rose. The two presumably became fast friends, and when Rose's bid on an old Victorian mansion proved too low, Abby pitched in her savings to help buy the place. The two generally seem to get along, though Rose does not approve of Abby's spiritual beliefs or her knack of disappearing whenever there is work to be done, and Abby wishes Rose would focus more on advertising rather than strict business.
Despite Charlie's stout heart, Abby dislikes him and blames him for the mansion's recent accidents, even trying to convince Rose to fire him. Though she recognizes Charlie's kind nature, she doesn't stand to tolerate his inexperience and would rather do away with him. On some occasions, he makes her considerably uncomfortable, sneaking up on her as if he's been watching her. Charlie, on the other hand, tolerates Abby, though he does comment that she can be weird and often gets on Rose's nerves.