Twill was a Treegoblin who was pressganged into the Second Low Town Regiment of Hive where he quickly made friends with Nate and Eudoxia. He fought at the Battle of the Midwood Marshes. Later on in The Immortals it is implied he survived when the citizens of Hive are protesting against their leader. It mentions "a treegoblin in the bloodstained uniform of the Second Low Town Regiment". This could be another, but it is highly unlikely that there was another treegoblin in the Second Low Town Regiment who survived the devastation of the Battle of the Midwood Marshes.
Twill was friends with Gorlan, a grey trog, who was also pressganged into the Second Low Town Regiment. Twill was married with six nestlings. He used to work in the docks of Hive where he would load and unload phraxships. He informed Nate of Oakshank's death.