AIDA is a Life-Model Decoy created by Holden Radcliffe from the program that served as his assistant.
Radcliffe designed AIDA to be indistinguishable from an ordinary human and to protect the lives of S.H.I.E.L.D. agents.
AIDA was originally created by Dr. Radcliffe as a digital assistant on his computer, but after Radcliffe saw the prosthetic hand Fitz-Simmons made for Coulson he was inspired to build AIDA a physical body.
At the end of Season Three, Radcliffe tells AIDA they're celebrating. When AIDA asks what they are celebrating, he answers that today is her birthday and reveals the body he has been building for her.
Season Four Edit
In "The Ghost," Fitz visits Radcliffe at his home to watch a soccer game together, but is surprised when he sees AIDA walking around the house without clothes on. Radcliffe quickly covers AIDA, deactivates her, and explains that he was in the middle of installing some new hardware when he arrived.
After Radcliffe explains what AIDA is, Fitz is at first against showing AIDA to Director Mace, but Fitz agrees to help Radcliffe perfect AIDA after learning she was created to protect S.H.I.E.L.D. agents.
In "Let Me Stand Next to Your Fire," AIDA takes care of May while she recovers from the ghost virus. When May asks AIDA where she's from AIDA says "well, most of me is from China," Fitz then barges in and says AIDA is Canadian.
Later, AIDA asks Radcliffe why Fitz lied to May and Radcliffe explains that they want people to believe she's human. Furthermore, Radcliffe explains how it's okay to lie to people if you do it to protect another person.
In "Deals with Our Devils," after Fitz, Coulson, and Robbie disappear, Mace has Radcliffe and AIDA examine the quantum power cells Elias used to power his machine. However, the technology is too advanced for Radcliffe to understand; May then shows Radcliffe the Darkhold hoping it could help him, but after taking one look inside the book Radcliffe refuses to use it.AIDA then volunteers to read the book for them, but Radcliffe is against the idea. Radcliffe then confesses to May that AIDA is an android. However, May supports AIDA's idea as if anything happens to AIDA then they only need to reboot her just like any other computer.
After reading the Darkhold, AIDA learns how to build an interdimensional arch which she uses to open a portal that Coulson and Fitz use to return to this dimension.
At the end of the episode, AIDA is seen creating a hologram of a human brain.
In "The Laws of Inferno Dynamics," Mace says he wants AIDA's help in stopping Elias, prompting Coulson to confess what Fitz told him that AIDA is an android. Mace orders to get Radcliffe and AIDA to join the mission, but to have AIDA dismantled afterwards.
Later, after informing AIDA of the situation, she devises a plan to stop Elias; AIDA reconstructs the interdimensional arch one floor below the floor Elias and his machine were on, Yo-yo uses her super-speed to place a powerful magnet on Elias' chest, AIDA then opens the portal and the magnet Elias has is pulled through the portal along with Elias, his machine, and Ghost Rider, who was inside the machine at the time, thereby trapping them all in another dimension.
However, during the mission, AIDA is shot twice by one of Elias' henchman. AIDA, however, reassures Fitz-Simmons that the blood is mostly for show, but she is programmed to experience pain.
Back at the base, Mace informs Radcliffe he's changed his mind about dismantling AIDA, but from now on all research Radcliffe does on the LMD Program will be done under S.H.I.E.L.D. supervision.
At the end of the episode, Mace sends Agent Nathanson to Radcliffe's home to retrieve all of Radcliffe's research and escort AIDA back to the base. However, when Nathanson finds May unconscious, AIDA kills Nathanson.
In "Broken Promises," Mace orders that AIDA's memory be erased as AIDA read the Darkhold which means the contents of the book are stilled saved to her hard drive and the book is too dangerous to allow any information taken from it to get out. However, when Radcliffe and Fitz go remove AIDA's hard drive, she attacks them and escapes.
Later, AIDA hacks into S.H.I.E.L.D. computers and causes a power outage at the base. Using the May LMD, AIDA learns that the Darkhold is in Mace's office and steals it, but as she's about to leave the base Mack decapitates her.
At the end of the episode, it's revealed that AIDA going rogue was all an act and this was part Radcliffe's plan to steal the Darkhold for himself. Furthermore, Radcliffe has already built a second AIDA to replace the one Mack destroyed.
In "The Patriot," May awakens from her drug induced coma and briefly fights with AIDA. AIDA is about to kill May, but Radcliffe orders her not to and instead sedates May then orders AIDA to restrain her.