Commander Evon Vorhalas was the older son of Count Vorhalas. According to his father, he was ambitious and desired a place on the General Staff. As his father's eldest son, he was also his heir, and so would be Lord Vorhalas. When Aral Vorkosigan refused to pardon his younger brother Carl, who was executed then for duelling, Evon swore revenge. That revenge took the form of a soltoxin gas grenade lobbed through Aral and Cordelia Vorkosigan's bedroom window; which did not kill either of them but did severely damage their unborn son.