F.R.I.D.A.Y. is a natural-language user interface created by Tony Stark, designed to work with his Iron Man armor. She served as Stark's main user interface computer system during the final battle between the Avengers and Ultron in Sokovia and to find information about Helmut Zemo. In contrast to J.A.R.V.I.S.'s voice code which was patterned after a male English accent, F.R.I.D.A.Y.'s is patterned after a female Irish one.
After J.A.R.V.I.S.'s matrices were uploaded into the Vision, Tony Stark sought to find a replacement user interface program for his Iron Man suits. Sorting through a pool of back-up programs that included ones named J.O.C.A.S.T.A. and T.A.D.A.S.H.I., he selected F.R.I.D.A.Y. and uploaded her into the Mark XLV armor to assist him during the Battle of Sokovia.
F.R.I.D.A.Y. monitored Ultron's attempts to escape into the internet when Vision attacked him; her mission was to track his attempts and ensure he did not succeed. Stark did not understand what was happening when Ultron activated his device to launch Novi Grad into the sky; he consulted F.R.I.D.A.Y. who quipped that Sokovia was going "for a ride". F.R.I.D.A.Y. helped Iron Man rescue a family trapped in a collapsing building.
Afterwards, she warned Stark that the Avengers could not afford to allow either the main Ultron or one of his sentries to touch the device that had raised Novi Grad, as this would cause the device to enter full reverse, ultimately destroying all life on Earth. Stark suggested capping the Vibranium with Thor, but F.R.I.D.A.Y. warned that this action could vaporize the city and everyone on it. Ultimately, Stark came up with a plan to create a heat seal so the rock would explode harmlessly, but this would only be an option following a total evacuation of Novi Grad.
Later, Stark used her to assist him during the Clash of the Avengers. After Scarlet Witch buried Stark under cars, F.R.I.D.A.Y. informed him that multiple contusions detracted, to which Stark replied that he detected that too. As Stark shot the repulsor blasts at Hawkeye, it suddenly deactivated. F.R.I.D.A.Y. informed him that many weapons system were offline. She found that Ant-Man was inside the mark XLVI, so she ejected him with the suit's extinguishing foam. At the end of the fight, Vision accidentally shot War Machine's Arc Reactor with his energy beam. After War Machine crashed on the ground, Stark asked F.R.I.D.A.Y. to read his vitals. She found that War Machine had heartbeat and informed Stark that emergency medical was on its way.
As Stark was in his helicopter on his way to the Raft, F.R.I.D.A.Y. informed him that Berlin police had found the psychiatrist who had been hired by the Joint Counter Terrorist Centre as soon Bucky Barnes had been captured and he met someone in the airport. Stark asked if she scanned his face, so F.R.I.D.A.Y. asked what she was look like, to which Stark answered he had always imagined her red head. F.R.I.D.A.Y said he must confusing her with someone else and continued. She said Broussard met Helmut Zemo, who had ran EKO Scorpion, a Sokovian covert kill squad. Broussard was found dead in hotel room in Berlin. The police also found a wig and facial prosthesis approximating the appearance Barnes. Stark asked her to deliver the information to Thaddeus Ross.
After a few hours in the HYDRA Siberian Facility, Stark learned that Barnes had killed his parents. As he tried to kill him, Captain America fought Stark back. Stark tried to shot Barnes with a missile, but F.R.I.D.A.Y. said the targeting systems was inaccurate, so Stark shot the missile to the entrance's axis without his helmet. As Stark and Captain America dueled, the latter pushed him to the wall and hit him hard several times. F.R.I.D.A.Y. said to Stark that he could not beat him hand to hand, so Stark said her to analyse his fighting pattern. F.R.I.D.A.Y. predicted where Captain America would hit next, so Stark held his shield and said to her "Let's kick his ass". The fight ended with Captain America taking Barnes with him and leaving Stark behind.
- J.A.R.V.I.S. - Predecessor
- Bruce Banner/Hulk
- Pepper Potts
- Happy Hogan
- Thaddeus Ross
- Team Captain America - Temporary Enemies
- Helmut Zemo
- In the comics, Friday was an A.I. created by Tony Stark to work as his secretary, her name originating from the term "girl Friday", meaning go-to person.
- One of F.R.I.D.A.Y.'s lines in Captain America: Civil War, "Targeting system's knackered, boss!", was a source of hilarity for Irish audiences.