Charles, new to the job, was panicking. He was a refugee from a big city. He was hoping for a nice easy ride to pension age in a small town and it all went wrong.
Wayne, a young man from Cracked Rock, taunted a band of trolls passing near the town, threw stones at them and tried to trip the cub. One of the trolls defended himself and knocked out Wayne's brother. This lead Charles to put the troll into custody until the USS Benjamin Franklin arrived to deal with this case.
This incident, the one among many the Franklin's crew encountered since the beginning of Operation Prodigal Son, finally decided Maggie Kauffman to make Carl a member of the crew as a gesture of cross-sapients friendship.