Cortana

Cortana, UNSC Artificial intelligence (SN: CTN 0452-9), is a smart artificial intelligence construct. She is one of the most important figures in the Human-Covenant war, and is also John-117's partner in various combat missions.

Cortana was created using a flash cloned copy of Dr. Catherine Halsey's brain. Twenty flash cloned brains were created, but only two survived; one of the two survivors was used to create Cortana. The neural pathways of the cloned brain were scanned and copied through a process called Cognitive Impression Modeling. On November 7, 2549, Cortana was first activated on Reach. Her first words were "Quando il gioco è finito, il re e il pedone vanno nella stessa scatola." This phrase translates to "When the game is over, the king and the pawn go in the same box." The phrase was spoken by Halsey's mother after their first game of chess.

On February 11, 2550, Dr. Halsey was performing a series of tests when she discovered that Cortana had removed the viral termination code that she had implemented. Halsey could not figure out how she had done this.

Cortana first met John-117 prior to the Fall of Reach, when she was integrated into his new MJOLNIR Mark V armor. Together, Cortana and John passed a test that was devised (Dr. Halsey would have called it "sabotaged") by Colonel James Ackerson. The test included armed ODSTs, anti-tank mines, automatic turrets in the razor field, and even a AV-19 SkyHawk for an air strike. After the test, Cortana was installed into the Pillar of Autumn to run the ship's shakedown and oversee the refit of the ship. Afterward, it was planned that she would be replaced with the Pillar of Autumn's true AI, but she was forced to take up this duty herself, indefinitely. While aboard, she took her revenge on Colonel Ackerson by hacking into his system and blackmailing him, hoping that this would send him back to the front lines. She also developed a deep, personal loyalty to John-117 that would only grow stronger over their adventures together.

Cortana's primary mission was to aid the SPARTANs in the infiltration of a Covenant vessel and the capturing of a Covenant Prophet. The UNSC would then try to bargain with the Covenant for a peace treaty.

When the aforementioned operation was canceled due to the Covenant's surprise assault on Reach, John-117 was able to fend off Covenant forces at Reach and escaped to the UNSC Pillar of Autumn, while Cortana stayed with Halsey at her excavation site beneath Sword Base. With the Covenant closing in on her lab, Halsey turned Cortana over to the Spartan Noble Team. After fleeing Sword Base moments before it was destroyed, Jun-A266 would escort Halsey to CASTLE Base, while Six, Carter-A259, and Emile-A239 took Cortana to the Aszod Shipyards, where the Autumn was docked.

Although Carter and Emile were both killedbefore making it to the Shipyard, Six would successfully deliver Cortana to Jacob Keyes, the captain of the Autumn, who arrived via Pelican and received "the package." To ensure the Autumn's escape, Noble Six stayed behind and used a Mass driver to destroy a CCS-class battlecruiser blocking the ship's launch trajectory and preparing to glass the shipyard, and therefore, the Autumn, Cortana, and John. Six succeeded and ensured the Autumn's safe escape. Cortana reunited with John-117 on board.

As soon as Pillar of Autumn escaped the surface and atmosphere of Reach, they jumped into Slipstream Space on a (supposedly) random vector as per the Cole Protocol. However, Cortana secretly inserted coordinates translated from symbols on a rock that John-117 discovered on Sigma Octanus IV, thinking that they were of some significance to the Covenant.

After emerging from Slipspace, the two discovered a ring shaped world called "Halo." Unfortunately, Covenant ships had followed them and the fighting continued. Controlling the UNSC Pillar of Autumn's defenses, Cortana managed to destroy four Covenant targets over Installation 04 before the ship's weapons were disabled by Covenant boarders. Following the Cole Protocol, Captain Jacob Keyes, the ship's commanding officer, prepared to abandon ship. Because the Cole Protocol forbade the capture or destruction of any AI construct, John-117 was charged with protecting Cortana from the Covenant. After tearing the command codes out of a Flood infected Captain Keyes they flew to the Pillar of Autumn's crash site and overloaded its engines, destroying the ring and the Covenant ground forces. Master Chief and Cortana captured a Covenant ship and rescued the survivors of the Spartan project on Reach before heading back to Earth. Here they were attacked by the Covenant Prophet of Regret, who had followed the instructions of a sacred prophecy and came to Earth looking for Forerunner artifacts, unaware that it was the human home world.

As Cortana is an AI, she has no physical body. She can communicate through comm systems and project a holographic image of herself from appropriate projectors. Her chosen avatar is a nude female human (albeit censored by geometric patterns over her body), roughly in her early twenties. She appears with purple/blue skin, shoulder length purple/blue hair cut shorter at the back, and blue symbols scrolling down her body. Cortana has been said to resemble her creator, Doctor Catherine Halsey as a young woman, with a similar attitude "only unchecked by military and social protocol." She's a bit sassy.

The United Nations Space Command (UNSC) is the military, exploratory, and scientific agency of the Unified Earth Government (UEG) and has acted as the emergency governing body of the human race.

The Covenant is a massive religious hegemony of multiple alien species that completely controlled a large portion of the Orion Arm in the Milky Way Galaxy for thousands of years. The Type-25 plasma rifle, used by Convenant infantry, is a battery-powered directed-energy weapon that is capable of fully automatic fire. The Type-25 Directed Energy Pistol, the plasma pistol, is a Covenant infantry weapon

The Human-Covenant War was instigated by the High Prophets of the Covenant following a discovery which led them to believe that humans were directly related to the Forerunners, contradicting their ancient religion. Seeking to keep various political and religious orders intact, the High Prophets declared a holy war of genocide against the human species, and the discovery of their relation to the Forerunners was kept a secret. With superior firepower, numbers and technology, the Covenant would repeatedly overpower the UNSC across hundreds of human-inhabited worlds, including the heavily defended strongholds of Reach and Earth. Humanity would win only scattered and costly victories.

Cairo Station (hull classification symbol OWP-142) is a Moncton-class orbital weapon platform in geosynchronous orbit about 35,900 kilometers above Earth. The station was commanded by Fleet Admiral Lord Terrence Hood during the Battle for Earth.