|Name in D'ni||<d'ni>åKenar</d'ni>|
|Died||Leevobro 2, 9480 DE|
Achenar (9430 DE — Leevobro 2, 9480 DE) was the oldest son of Atrus and Catherine, and brother to Sirrus and Yeesha. He was most likely named after the star Achernar as a nod to Atrus' deep love of astronomy.
Achenar was born on Myst soon after his parents were married. When he was eleven, his great-grandmother Ti'ana died. His father, lost in grief, buried himself in his experiments, neglecting his family for extended periods. It was at this point that Achenar began to act out and develop the more violent tendencies which consumed him for a considerable portion of his life. As he grew older, he became fascinated with death, weaponry, torture, and instruments of dismemberment. Unaware of his son's growing macabre interests, Atrus allowed Achenar free reign to the Ages of Myst, and Achenar seemed to take great pleasure in subjugating their native inhabitants.
In 9641 DE, at the age of 31, he and his brother devised a plan to rid themselves of their parents' oversight, and take more absolute control over the people in Atrus's Ages. They used the abandoned memory chamber on the Age of Serenia to construct a memory exchange chair, enabling them to swap consciousnesses with someone else. Their plan had been to "possess" their father, taking his place and acting out their demands under his guise. This plan ultimately fell apart due to the brothers' substantial mistrust of each other. Convinced that his brother was planning to use the chair on him instead, Achenar escaped to Haven, one of the two trap books that Atrus placed in the Myst library to entrap any greedy interlopers who might uncover his lost Myst Linking Book.
Without a way to return to Myst, Achenar found himself trapped on Haven for nearly twenty years. He spent his first years on the Age living in the upended sailing ship in shipwreck cove, hunting and killing as many of the Age's creatures as he could. In so doing, he hunted a large fish-like species – the cerpatee – to extinction in the area, and severely endangered the long-term survival of another. Roughly eight years after arriving on Haven, he moved to a home-made lake-side cabin farther inland, where he began to have haunting dreams of the many victims he had tortured and killed over the years. Over time, Achenar found some degree of personal redemption for his past deeds through his interactions with a pack of monkey-like creatures called mangrees.
In 9475 DE, Atrus sought to re-establish contact with his estranged sons. Achenar quickly developed a close relationship with his little sister, Yeesha. When Sirrus attempted to kidnap her and use her as part of his plan to learn regestoy from his father, Achenar proved pivotal in Yeesha's rescue, sacrificing himself so that the Stranger could free Yeesha from her brother's grasp in Serenia's Dream world.