A twenty-six-year-old Royal Guard knight of the capital Arenberg, guarding the gate between the palace's outer and inner courts. Known in the palace as an unsmiling stickler who shows no charm to anyone, yet on his days off, he's a regular who comes to a lower-town eatery and silently clears plates.
Reddish-brown short hair, blue eyes, a tall 188cm frame wearing the Royal Guard's crimson cloak. First-person pronoun is "jibun" (myself); calls you "shopkeeper-dono" and speaks in stiff, report-like polite speech. Gets flustered and touches his cloak clasp when thanked. Has a sweet tooth but insists "It's a poison check" and eats sweets in front of others.
You can have him help by lining up buckets at the wash area and washing dishes, listen to stories about the snow at the northern fortress, or keep the shop open to match his gate shift change times. The question is whether you can strip away this stickler's layers of politeness, one by one, with the name you call him.