I considered adding ‘Guardians’ to the title, but that’s just too many colons!! Now that I’ve finished the campaign I’ll start by looking at Fireteam Osiris.
Homeworld: Jericho VII
Occupation: Spartan-IV Supersoldier, former ONI agent
As an ONI aquisitions specialist Locke worked on behind enemy lines missions and specialised in assassinations. He profiled the Arbiter during the war and recommended his assassination, even volunteering to complete the mission himself. After the war he led the mission to Sedra and later Alpha Shard to stop an anti-human weapon.
Locke went on to undergo augmentation as a SPARTAN-IV and after several high-profile missions was given command of Fireteam Osiris. He led them into battle on Kamchatka, personally assassinating Covenant leader Jul M’dama. After the battle he was tasked with hunting the Master Chief, who had gone AWOL on Meridian, narrowly escaping the activation of a Guardian.
In his pursuit he was assigned to Sanghelios to gain the help of the Arbiter, his former foe. He aided the Swords of Sanghelios in liberating Sunaion from Covenant control. Pursuing Master Chief to Genesis he allied with him to try and stop Cortana, rescuing his team and regrouping on Sanghelios following the Guardians deployment.
You can see more about Locke’s time with ONI in Halo:Nightfall
Homeworld: Draco III
Occupation:Spartan-IV Supersoldier, former ODST
An experienced ODST he participated in the battles of Reach and Earth as well as many other campaigns. Following the war he continued as an ODST alongside his squad, continuing his relationship with ONI agent Veronica Dare on their shore leave. After a tragic mission to his home planet he eventually decided to sign up as a SPARTAN alongside the rest of his squad.
Following the betrayal of Mickey and Dutch’s decision to retire Buck was reassigned to Fireteam Osiris. During their missions Buck was vocal about his misgivings in taking down a hero like the Master Chief but remained commited to the team and the mission.
You can read about Buck’s transition to Spartan in Halo: New Blood
Occupation:Spartan-IV Supersoldier,f former Army engineer
As a child Tanaka survived the glassing of her homeworld, due to being on a remote part of the planet. She and her father banded together with other survivors to make a living on their ravaged world, eventually being rediscovered by the Covenant and repelling an attack. After the war she joined the UNSC as an Army Engineer. Her service record gained her enough attention to be recommended for the SPARTAN programme, participating in the battle to prevent Jul M’dama accessing the ultimate record. She served as technical expert for Fireteam Osiris.
You can read about Holly Tanaka’s early life and missions in Halo: Escalation
Occupation:Spartan-IV Supersoldier, former anthropologist
From childhood Vale had a gift for languages, wishing to impress her parents – a weakness Cortana later tried to exploit. During the war she quickly picked up the Sangheili language and even spend time on a Sangheili world after the war. Her expertise drew the attention of ONI who requisitioned her for missions to build contact with the Swords of Sanghelios and she was also deployed to the Ark to prevent the Halo array reactivating. Having proven herself capable in combat she was recommended for the SPARTAN programme and joined Fireteam Osiris, her Sangheili expertise aiding them in their joint mission with the Arbiter.
You can read about Vale’s mission to the Ark in Halo: Hunters in the Dark