C. Junior - Junior for short - is Mr. Conductor's cousin. Like his cousin, he is at a regular height on Sodor and the Magic Railroad - anywhere else, he shrinks to a height of 24 centimetres (ten inches).
Junior was called by Mr. Conductor to go to Sodor to help find the source of the gold dust. Junior was almost out of gold dust himself, and so he brought Lily to help him. When they reached the windmill he took a ride on it when no one was looking, but the wind was too strong and he was flung onto Diesel 10, losing his beach bag in the process. Diesel 10 took him to the the scrapyards and flung him onto James. In the nick of time, Junior teleported himself and James to safety using the last of the gold dust.
After Diesel 10 fell onto a barge and the gold dust was restored, Junior kept his promise to Lily to give her a little bit of gold dust. He decided not to go back to the beach, opting instead to become the new Conductor of Shining Time.
Junior enjoys relaxing on the beach and playing pranks - Thomas mentioned he once stuck party streamers down his funnel. He often gets into trouble. Everything he does though is in good heart, if pranking can be considered in good heart.