Aaron and Sarah Dennison

Aaron and Sarah Dennison, aka DCAK (DC Audience Killer), are the main antagonists of the Alex Cross novel Double Cross. The Dennisons are siblings and incestuous lovers, disguised as Cross' psychiatric patients, under aliases of Sandy Quinlain and Anthony Demao. The two record snuff films of notorious people or killings of people in notorious, crowded places, leaving taunts to investigators and publicizing the videos in demands of attention. Websites are set up detailing timelines of the killers and victims. Crime author Tessa Olsen is the first, thrown off her apartment balcony, leaving behind a Hallmark greeting card and the video of the murder ending with "In your honor". Matthew Jay Walker is killed while acting in a play, the video posted on a website, revealing the desire for infamy. As "Quinlain" and "Demao", Sarah poses as a hypersexual woman and Aaron a vet having killed his partner from terminal illness, the "partner" named Matthew as a nod Cross doesn't get. Cross deduces the DCAKs taking on various alter-egos with each murder, further confirmed as the crimes escalate. A copycat even gets inspired to kill two children in a Richard Nixon mask. Kyle Craig, The Mastermind, is revealed to have been an inspiration for the duo when Cross travels to Florence and finds out Olsen interviews Craig for her for her book. As further mental torture and ruse implementation, Sarah masturbates Aaron in Cross' waiting room, them meet at a coffee shop and make out while revealing they're siblings. By then, Aaron says to Sarah Craig texted them and wants to meet them, leaving them officially revealed as the DCAKs. The Dennisons then text Cross and warn of another murder, and the duo isn't stopped from killing a pregnant woman at the Smithsonian Air and Space Museum. They then track the copycat and throw him off a helicopter onto a roof, revealing the Nixon killer as assigned agent Brian "Kitz" Kitzmiller. Aaron then is disguised as "reporter" Neil Stephens to punch Bree Stone and run. Pretending a ruse that "Sandy's leaving" and kisses "Anthony" before heading off to Michigan, the duo then regroup and kidnap colleague of Cross, John Sampson. Leaving a phone to give directions to their layer, the duo ties Cross and girlfriend Bree Stone to chairs and both are held hostage. The duo reveal themselves and that suspect Timothy Bell, brother of dead murderer Michael Bell, was murdered by them. The duo get pissed off by the two cops, but Stone breaks free and kills Sarah. Aaron's chased to a Mexican restaurant and gets stabbed to stop him. Craig arrives and reveals to have gotten in contact for the climactic fight between then all. Stone shoots and seemingly kills Craig, but Craig gets up and fires back at Stone, missing intentionally and escaping. Cross arrests Aaron, Aaron swearing revenge from the hospital.