His older sister Odette died suddenly at the age of sixteen under mysterious circumstances. Her death had a profound effect on Stephen, who suspected from the beginning that his brother Letholdus III was responsible.
Stephen married Maria, a minor noblewoman, at the age of twenty four. The two had a son, Stephen II. At the time, Letholdus had not yet married and had no heirs, making Stephen's infant son next in line after him. This created further tension between the brothers.
Upon their father's death, Letholdus assumed the throne. Stephen began to express his fears that his brother would use his newfound power to cause them harm.
One night, three assassins broke into the family's castle near Tyre, killing Stephen, Maria, and their infant son. The murderers were caught, tortured, and eventually executed, but they never provided a motive for the killings or named the one who ordered them. It is generally believed that Letholdus orchestrated the murders to keep the line of succession pure.