Yonas is a member of expedition squad of Harpers, together with Meygan and Karrow, led by Lassandra. Quickly after meeting the party and regardless of initial dialogue decisions of the player Yonas is ambushed and corrupted by Shadows, turning into lvl 5 Zombie. Immediately after Yonas's demise the battle with ambushing Shadows is commenced. The blighted Harper sides with shadows and shoud inevitably be killed.
If the group leader Lassandra has survived the fight, she will talk to the player again and mark the Last Light Inn on their map.
Should the party come to this place soon enough, they might find members of Lassandra's group mourning Yonas near Last Light Inn docks.