Ørn's guardian and right-hand man, the hunter Halfdan led the Moonstalkers, the advance guard of the Ursus Guard Legion. Wolf Geri, his Arche beast mech, was a ferocious force in frontal assaults, while the Moonstalkers under his command were more than capable of finding openings to snipe down giant beasts.
When not charging the enemy aboard Wolf Geri, Halfdan was a dab hand with a behemoth gun. After paralyzing his enemy, he would move in to engage at close quarters with a heat knife. Despite his rank, he was more a hunter than a military man; in fact, he was Veck's finest chimera-killer. His ability as a scout to maintain his cool in the face of attacking hordes of chimeras and swiftly dismember them won even more praise from all sides than his twin brother Sturla's dashing valor.
Notably, he was a chimera hunter before joining the Ursus Guard Legion at the invitation of Harald Lodbrok, the previous commander. Under Harald, he and his brother Sturla became master sergeants in charge of frontline forces. Because the new Ursus Guard Legion was short on experienced officers, Halfdan and Sturla stepped up and accepted promotions to 2nd lieutenant and lieutenant respectively in order to better aid Ørn.