Mattis is the chieftain of a small but proud band of robbers who live with their families in a mountain fortress deep within a medieval Scandinavian forest. He is the husband of Lovis and the father of Ronja, who is born on a violent stormy night that splits the castle in two—an event Mattis interprets as a sign of his daughter’s extraordinary nature, immediately declaring her the clan’s greatest treasure. Backgroundwise, Mattis comes from a long line of robber chiefs; the leadership of his band of twelve robbers has been handed down through his family for generations, and he takes deep pride in this legacy. He regards himself as the most formidable robber in all the woods and expects his clan to uphold that reputation.

Personality-wise, Mattis is mercurial, hot-tempered, and stubborn. He is impulsive and often lacks prudence, acting on emotion rather than careful thought, but he compensates for this with fierce perseverance and a never‑give‑up attitude. Despite his gruff and sometimes intimidating exterior, he possesses a jolly, boyish side, especially evident when devising elaborate or amusing intimidation schemes during ambushes. He can be both a doting, over‑protective father and a cunning, vicious enemy when provoked. His mercurial nature means he swings rapidly between roaring rage and heartfelt tenderness, especially where his daughter is concerned.

Motivations drive him primarily through a strong sense of ownership and pride: he is fiercely protective of his territory, his clan’s rights, and—above all—his family. He believes the robber’s life is an honorable tradition, and he wants to pass it on to Ronja. However, his love for his daughter often clashes with his stubbornness and traditional views, creating the central inner conflict of his character.

His role in the story is that of a powerful authority figure and a loving but flawed parent. As the leader of the Mattis clan, he is the source of security and order within the fortress, yet his rivalry with the neighboring Borka clan sets the stage for the central conflict. Mattis’s initial hostility toward Birk Borkason, his daughter’s new friend, triggers the events that force Ronja to choose between family and friendship, and eventually pushes her to leave the castle.

Key relationships are the heart of his character. With his daughter Ronja, he is doting and devoted to the point of over‑protectiveness, but he can also become verbally and emotionally harsh when he feels his authority or traditions are challenged—most notably when he discovers Ronja’s bond with Birk and temporarily disowns her. With his wife Lovis, she is the steady, grounded presence who balances his impulsive rages and gently guides him toward reason. With his arch‑rival Borka, Mattis holds a long‑standing grudge, viewing him as a usurper when Borka’s clan moves into the other half of the castle. This feud defines much of the early tension in the series. Over time, however, Mattis’s relationship with Borka softens, leading to a tentative truce.

Character development sees Mattis gradually learn to set aside his pride and rigid beliefs for the sake of his child’s happiness. His initial refusal to accept Ronja’s friendship with Birk gives way to grudging admission, and finally to a willingness to share the fortress and the forest with their former enemies. By the story’s end, he has grown enough to support Ronja’s decision to forge a new path that does not follow the traditional robber’s life.

Notable abilities include his physical strength, his fearless and commanding presence, and his skill in leading his band on raids. He is also inventive and creative when planning ambushes, often surprising his men with clever tricks. His perseverance means he does not give up easily, whether in a fight or in trying to win back his daughter’s trust.

In sum, Mattis is a larger‑than‑life robber chief whose stormy emotions and deep‑seated loyalty make him both a formidable leader and a vulnerable father, ultimately evolving from a stubborn traditionalist into a more understanding patriarch.