Catherine Halsey
Brilliant creator of the controversial Spartan program and Cortana AI, Dr. Catherine Halsey has recently found herself in the custody of the Covenant's Supreme Leader, Jul 'Mdama, as revealed by events that unfolded in the Spartan Ops expansion to Halo 4, as well as the Escalation comic book series. Driven by her scientific fascination and perpetual curiosity, Dr. Halsey seeks to unlock the secrets of a recent Forerunner technological find—but soon discovers evidence of an event so frightening, it prompts Halsey to contact the UNSC in search of support.
Captain Lasky
Captain of the UNSC flagship Infinity, Captain Thomas Lasky serves as supervisor to Blue Team and Fireteam Osiris. The young captain has already seen plenty of action, having been caught up in the Master Chief’s adventures on Requiem not long ago. When Blue Team defies his direct orders, Captain Lasky is left with no other choice but to send Fireteam Osiris after the AWOL operatives, tasking Spartan Locke with their retrieval.
Sarah Palmer
A veteran of the Human-Covenant War, Sarah Palmer was augmented as one of the first Spartan-IV super-soldiers, and now serves as the Commanding Officer of the Spartan contingent aboard the UNSC Infinity. An exceptional and fearless pilot, Spartan Palmer never fails to complete her mission—whether it be a risky deployment or a hasty extraction.
Jul ‘Mdama
A cunning Sangheili warrior, Jul ‘Mdama has used his success in securing an alliance with the Prometheans to cement his position as the Covenant’s Supreme Leader. Having recently fallen in with Dr. Catherine Halsey, ‘Mdama seeks to unlock the secrets of Forerunner Holy Relics, using their technology as a means of gaining power and control over all others throughout the galaxy.
Arbiter
Not all Sangheili are eager to follow Jul ‘Mdama’s new reign. Many choose to follow the Arbiter: a respected leader who now commands an alliance known as the Swords of Sanghelios. These rebellious Elites have decided to make war with the Covenant in an effort to liberate their homeworld. Guided by the Arbiter’s cunning, focus, and resolve, the Swords have enjoyed many victories—yet Sanghelios still struggles to rid itself of its Covenant blight.