Sif

Sif was the UNSC Shipping Operations AI aboard the Tiara space station, in orbit above the colony world of Harvest. Near the center of the Tiara was a room which housed her data center.

Biography
She is in charge of Harvest's shipping operations which included the balancing of the Tiara, the transporting of human and shipping traffic up and down the space elevator, and control of the passenger and cargo transport in and out of the Tiara, as well as shipping manifests and keeping cargo on schedule. The AI Mack would often flirt with Sif, usually to her annoyance and frustration.

Battle of Harvest
As the Tiara was invaded by Jiralhanae, Yanme'e and Unggoy from the Rapid Conversion, Sif was incapacitated by Loki, who used a military-grade virus to delete her restraint algorithms and operational codes in an attempt to prevent her from falling into Covenant hands. Her core logic was later partially restored by the Huragok Lighter Than Some, although in the absence of emotional self-control programs, she came back online rampant. Despite her rampant and severely weakened state, she rejoined the fight to rescue the citizens of Harvest. With Lighter than Some continuing to repair her systems on the fly, Sif assisted Loki in rebalancing the number-seven strand after a Jiralhanae attack threatened to destroy it.

Following the evacuation, when Loki decided to destroy her, she agreed and helped him convince Mack to allow it. She told Loki to relay to Mack that she loved him. Soon after, Loki shot a mass driver round into her data center, destroying her and the Tiara. She attempted to go through the many emotions that rampancy afforded her; however, she found them all to be untrue to her. She ultimately died content, feeling that she had lived a fuller life than her makers had ever thought possible.

Appearance
Sif's chosen avatar was in the form of a woman wearing an ankle-length sleeveless gown and long golden hair, with a red poncho that she draped over her shoulders. She spoke with the accent of Nordic royalty. She chose this accent because many of Harvest's settlers were from Earth's American heartland, who could trace their ancestry back to Scandinavia. As a remnant of her human brain donor, Sif enjoyed the sensation of cargo containers running along Tiara's elevator strands, similar to how her human counterpart loved grooming her own hair twice a day.

Trivia

 * Sif is the wife of Thor in Norse mythology.
 * Much as the gods Sif and Loki were often at odds in Norse mythology, Sif is constantly irritated with Mack's (Loki's) presence.
 * In the Halo: Contact Harvest audio book, Jen Taylor, the voice of Cortana, takes over the narration when Sif is the focus of events.

List of appearances

 * Halo: Contact Harvest