Lucien Morel is a central character in the narrative, first introduced as a careless and occasionally irresponsible boy and the best friend of Annette. He resides in a Swiss mountain village with his mother and older sister, Marie. Though described as book-dumb and lazy in his studies, he possesses a natural gift for woodcarving, a skill that grows increasingly significant.

His deep but tumultuous friendship with Annette is often marked by arguments and reconciliations. A pivotal moment occurs during a confrontation with Annette's younger brother, Dani. Upset after a conversation, Lucien threatens to throw the boy's pet ermine, Klaus, off a cliff. In the ensuing struggle, Klaus bites Lucien and falls. Dani attempts a rescue and plummets from the cliff, suffering a severe leg injury that leaves him permanently dependent on crutches. Lucien is immediately horrified and consumed by guilt, believing himself responsible for the tragedy.

In the aftermath, Lucien becomes an outcast in the village, shunned by many. The most significant rejection comes from Annette, who develops a deep and cold hatred for him and refuses all his attempts to apologize or reconcile. This period brings Lucien profound despair; he even contemplates suicide before an old hermit and woodcarver named Peguin intervenes and counsels him.

Under Peguin's mentorship, Lucien dedicates himself to woodcarving and hones his craft. As an act of repentance and an attempt to reconnect with Dani, he spends weeks meticulously carving a detailed Noah's Ark filled with animals. When he presents the gift, Annette intercepts it, destroys the ark in front of him, and banishes him from ever approaching her brother again, deepening his hopelessness.

Later, Lucien decides to enter a school competition, carving a wooden horse to give to Dani, hoping the first prize would make the gift more meaningful. On the eve of the competition, Annette, driven by resentment and jealousy over the quality of his work, destroys the carving. Her eventual confession leads to a turning point. Lucien immediately forgives her, beginning a slow and difficult process of mending their fractured friendship.

The central conflict resolves through a determined and courageous act. After learning from his sister about a renowned orthopedic doctor staying in a distant city who could potentially cure Dani, Lucien undertakes a desperate nighttime journey through a blizzard to reach him before he departs. Exhausted and nearly frozen, he successfully finds the doctor and convinces him to examine Dani. The subsequent operation is a success, allowing Dani to walk again without crutches. This selfless act finally enables a complete reconciliation with Annette, dissolving the last barriers of resentment and fully restoring their friendship.