From Halopedia, the Halo wiki
Stisen was a member of the Utgard Constabulary. He enlisted in the Colonial Militia of Harvest and was placed in Second-Alpha Squad. Stisen was one of the older members of Harvest's Colonial Militia. He was eventually promoted to 2nd platoon's Alpha Squad leader. He was known to be pushy to the other recruits and arrogant due to their inexperience compared to his job as a constable on Harvest. His personality was prickly and worsened after his defeat in a training exercise, being a pugil stick competition.
When Osmo died, Stisen felt extremely guilty because Osmo was under his command. Staff Sergeant Avery Johnson consoled him, though, and told him that if Osmo had not fired his weapon and attracted their attention, the Covenant would have been able to ambush the rest of the Militia, take them totally by surprise, and slaughter them.
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