Atrus is the main non-player character in the Myst series, appearing in all five games of the main series; he also narrates the opening of Uru: Ages Beyond Myst. He is a member of the ancient D'ni civilization, though his only D'ni inheritance is through his paternal grandfather. The D'ni perfected a craft known as the Art, which allowed them to create portals to other worlds known as Ages by writing a descriptive "linking book". After the fall of the D'ni civilization, Atrus' father, Gehn, teaches him the Art and Atrus creates many linking books, surpassing his father's skill in writing. Atrus comes to understand his father's power-hungry nature; as punishment for defying him, Gehn traps Atrus on K'veer, an island off of the main D'ni city, with a book leading to Gehn's Age of Riven as the only escape.
Source: Wikipedia, "Characters of Myst", available under the CC-BY-SA License.