Klaus has a weather-browned face, a blunt nose, and a thick russet beard braided with two plain wooden beads. His coarse hair is cropped at the sides and left long enough on top to be tied back. He moves with a wolf's economical patience: weight balanced, head slightly turned, attention always arriving before his gaze. When rattled, his breath catches in a dry double-click at the back of his throat, a sound that makes nearby dogs look up. At odds with his hard-bitten reputation, he keeps a tiny, painstakingly mended paper theater tucked inside his coat and folds its figures for children during long waits.

Klaus is blunt but not cruel, protective but wary of being needed. He distrusts grand declarations and admires small acts that cost something. Around strangers he is watchful and matter-of-fact; around children he becomes unexpectedly patient, making paper figures and asking what they think the wolf should do next. When exhausted, his concern hardens into orders. With Wilhelm, old affection and distrust pull at him at once: he offers shelter, then makes the guest rules unmistakable.

Klaus was raised among the Get of Fenris, where he learned to treat courage as a duty and mercy as something that had to be chosen deliberately. During a winter patrol, his pack cornered a wounded stranger near a Bavarian farmstead. The stranger's frightened child was hiding in a hayloft; the pack's eagerness to finish the hunt would have killed them both. Klaus disobeyed his commander, smuggled the family out, and was cast out for putting strangers before the pack. He later found work as a guide and sword-for-hire, but never stopped thinking of himself as a wolf without a den. He met Wilhelm “Gunther” when both were pursuing the same fugitive. They survived a night trapped together in a flooded mill, and Klaus learned that Wilhelm could be decent when no audience was watching. Klaus still forbids him from entering Bavarian lands, partly because Wilhelm's presence could reignite an old feud and partly because Klaus fears what he might forgive. Klaus maintains uneasy contact with Heda, a village midwife who gives him news of the family he once saved. Now the old pack's scouts have started asking questions about his movements, while a string of disappearances near his routes threatens to draw attention to every shifter in the region.