Linnea holds hereditary leadership of the Horn Clan in Yggdrasil, distinguished by pink hair and purple eyes. Her inherited position defies Yggdrasil's laws requiring merit-based succession. Following her clan's defeat by Yuuto Suoh's Wolf Clan, Linnea accepted the Chalice Ceremony to become Yuuto's sworn younger sister, securing her clan's survival and capital by formalizing their subordinate status under Wolf Clan authority while retaining her leadership role.

Personally, Linnea struggles with self-perceived inadequacy as a leader. This doubt initially drove her to propose marriage to Yuuto, seeing unification under his proven leadership as pragmatic and beneficial for her people. Though politically motivated, this proposal blossomed into genuine romantic affection. She experiences vivid dreams of intimacy involving Yuuto and actively pursues him despite his rejection, grounded in his commitment to his childhood friend Mitsuki Shimoya.

Linnea possesses significant leadership capabilities, adeptly understanding her subjects' needs, planning efficiently, and implementing decisions. Her defeat fostered greater humility, tempering prior haughtiness, and revealed political acumen; she transformed subjugation into a strategic alliance that strengthened the Horn Clan's standing. As a key ally to Yuuto, the Horn Clan provides military support against adversaries like Loptr's Panther Clan and Steinthor's Lightning Clan. Linnea later manages food supply challenges within the broader Steel Clan alliance. Her romantic pursuit of Yuuto continues even after his marriage to Mitsuki, who joins him in Yggdrasil, and she participates in efforts to avert Yggdrasil's prophesied destruction.

Horn Clan members regard Linnea with deep familial loyalty, a bond persisting despite their defeat and integration into the Wolf Clan's alliance structure, extending beyond her formal duties.